January 2025 - Linux-stable-mirror

[PATCH v2 1/9] btrfs: fix double accounting race when btrfs_run_delalloc_range() failed

by Qu Wenruo

[BUG] When running btrfs with block size (4K) smaller than page size (64K, aarch64), there is a very high chance to crash the kernel at generic/750, with the following messages: (before the call traces, there are 3 extra debug messages added) BTRFS warning (device dm-3): read-write for sector size 4096 with page size 65536 is experimental BTRFS info (device dm-3): checking UUID tree hrtimer: interrupt took 5451385 ns BTRFS error (device dm-3): cow_file_range failed, root=4957 inode=257 start=1605632 len=69632: -28 BTRFS error (device dm-3): run_delalloc_nocow failed, root=4957 inode=257 start=1605632 len=69632: -28 BTRFS error (device dm-3): failed to run delalloc range, root=4957 ino=257 folio=1572864 submit_bitmap=8-15 start=1605632 len=69632: -28 ------------[ cut here ]------------ WARNING: CPU: 2 PID: 3020984 at ordered-data.c:360 can_finish_ordered_extent+0x370/0x3b8 [btrfs] CPU: 2 UID: 0 PID: 3020984 Comm: kworker/u24:1 Tainted: G OE 6.13.0-rc1-custom+ #89 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs] pc : can_finish_ordered_extent+0x370/0x3b8 [btrfs] lr : can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] Call trace: can_finish_ordered_extent+0x370/0x3b8 [btrfs] (P) can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] (L) btrfs_mark_ordered_io_finished+0x130/0x2b8 [btrfs] extent_writepage+0x10c/0x3b8 [btrfs] extent_write_cache_pages+0x21c/0x4e8 [btrfs] btrfs_writepages+0x94/0x160 [btrfs] do_writepages+0x74/0x190 filemap_fdatawrite_wbc+0x74/0xa0 start_delalloc_inodes+0x17c/0x3b0 [btrfs] btrfs_start_delalloc_roots+0x17c/0x288 [btrfs] shrink_delalloc+0x11c/0x280 [btrfs] flush_space+0x288/0x328 [btrfs] btrfs_async_reclaim_data_space+0x180/0x228 [btrfs] process_one_work+0x228/0x680 worker_thread+0x1bc/0x360 kthread+0x100/0x118 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1605632 OE len=16384 to_dec=16384 left=0 BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1622016 OE len=12288 to_dec=12288 left=0 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1634304 OE len=8192 to_dec=4096 left=0 CPU: 1 UID: 0 PID: 3286940 Comm: kworker/u24:3 Tainted: G W OE 6.13.0-rc1-custom+ #89 Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: btrfs_work_helper [btrfs] (btrfs-endio-write) pstate: 404000c5 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : process_one_work+0x110/0x680 lr : worker_thread+0x1bc/0x360 Call trace: process_one_work+0x110/0x680 (P) worker_thread+0x1bc/0x360 (L) worker_thread+0x1bc/0x360 kthread+0x100/0x118 ret_from_fork+0x10/0x20 Code: f84086a1 f9000fe1 53041c21 b9003361 (f9400661) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Oops: Fatal exception SMP: stopping secondary CPUs SMP: failed to stop secondary CPUs 2-3 Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: 0x275bb9540000 from 0xffff800080000000 PHYS_OFFSET: 0xffff8fbba0000000 CPU features: 0x100,00000070,00801250,8201720b [CAUSE] The above warning is triggered immediately after the delalloc range failure, this happens in the following sequence: - Range [1568K, 1636K) is dirty 1536K 1568K 1600K 1636K 1664K | |/////////|////////| | Where 1536K, 1600K and 1664K are page boundaries (64K page size) - Enter extent_writepage() for page 1536K - Enter run_delalloc_nocow() with locked page 1536K and range [1568K, 1636K) This is due to the inode has preallocated extents. - Enter cow_file_range() with locked page 1536K and range [1568K, 1636K) - btrfs_reserve_extent() only reserved two extents The main loop of cow_file_range() only reserved two data extents, Now we have: 1536K 1568K 1600K 1636K 1664K | |<-->|<--->|/|///////| | 1584K 1596K Range [1568K, 1596K) has ordered extent reserved. - btrfs_reserve_extent() failed inside cow_file_range() for file offset 1596K This is already a bug in our space reservation code, but for now let's focus on the error handling path. Now cow_file_range() returned -ENOSPC. - btrfs_run_delalloc_range() do error cleanup <<< ROOT CAUSE Call btrfs_cleanup_ordered_extents() with locked folio 1536K and range [1568K, 1636K) Function btrfs_cleanup_ordered_extents() normally needs to skip the ranges inside the folio, as it will normally be cleaned up by extent_writepage(). Such split error handling is already problematic in the first place. What's worse is the folio range skipping itself, which is not taking subpage cases into consideration at all, it will only skip the range if the page start >= the range start. In our case, the page start < the range start, since for subpage cases we can have delalloc ranges inside the folio but not covering the folio. So it doesn't skip the page range at all. This means all the ordered extents, both [1568K, 1584K) and [1584K, 1596K) will be marked as IOERR. And those two ordered extents have no more pending ios, it is marked finished, and *QUEUED* to be deleted from the io tree. - extent_writepage() do error cleanup Call btrfs_mark_ordered_io_finished() for the range [1536K, 1600K). Although ranges [1568K, 1584K) and [1584K, 1596K) are finished, the deletion from io tree is async, it may or may not happen at this timing. If the ranges are not yet removed, we will do double cleaning on those ranges, triggers the above ordered extent warnings. In theory there are other bugs, like the cleanup in extent_writepage() can cause double accounting on ranges that are submitted async (compression for example). But that's much harder to trigger because normally we do not mix regular and compression delalloc ranges. [FIX] The folio range split is already buggy and not subpage compatible, it's introduced a long time ago where subpage support is not even considered. So instead of splitting the ordered extents cleanup into the folio range and out of folio range, do all the cleanup inside writepage_delalloc(). - Pass @NULL as locked_folio for btrfs_cleanup_ordered_extents() in btrfs_run_delalloc_range() - Skip the btrfs_cleanup_ordered_extents() if writepage_delalloc() failed So all ordered extents are only cleaned up by btrfs_run_delalloc_range(). - Handle the ranges that already have ordered extents allocated If part of the folio already has ordered extent allocated, and btrfs_run_delalloc_range() failed, we also need to cleanup that range. Now we have a concentrated error handling for ordered extents during btrfs_run_delalloc_range(). Cc: stable(a)vger.kernel.org # 5.15+ Fixes: d1051d6ebf8e ("btrfs: Fix error handling in btrfs_cleanup_ordered_extents") Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/extent_io.c | 37 ++++++++++++++++++++++++++++++++----- fs/btrfs/inode.c | 2 +- 2 files changed, 33 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 9725ff7f274d..417c710c55ca 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1167,6 +1167,12 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, * last delalloc end. */ u64 last_delalloc_end = 0; + /* + * Save the last successfully ran delalloc range end (exclusive). + * This is for error handling to avoid ranges with ordered extent created + * but no IO will be submitted due to error. + */ + u64 last_finished = page_start; u64 delalloc_start = page_start; u64 delalloc_end = page_end; u64 delalloc_to_write = 0; @@ -1235,11 +1241,19 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, found_len = last_delalloc_end + 1 - found_start; if (ret >= 0) { + /* + * Some delalloc range may be created by previous folios. + * Thus we still need to clean those range up during error + * handling. + */ + last_finished = found_start; /* No errors hit so far, run the current delalloc range. */ ret = btrfs_run_delalloc_range(inode, folio, found_start, found_start + found_len - 1, wbc); + if (ret >= 0) + last_finished = found_start + found_len; } else { /* * We've hit an error during previous delalloc range, @@ -1274,8 +1288,21 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, delalloc_start = found_start + found_len; } - if (ret < 0) + /* + * It's possible we have some ordered extents created before we hit + * an error, cleanup non-async successfully created delalloc ranges. + */ + if (unlikely(ret < 0)) { + unsigned int bitmap_size = min( + (last_finished - page_start) >> fs_info->sectorsize_bits, + fs_info->sectors_per_page); + + for_each_set_bit(bit, &bio_ctrl->submit_bitmap, bitmap_size) + btrfs_mark_ordered_io_finished(inode, folio, + page_start + (bit << fs_info->sectorsize_bits), + fs_info->sectorsize, false); return ret; + } out: if (last_delalloc_end) delalloc_end = last_delalloc_end; @@ -1509,13 +1536,13 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl bio_ctrl->wbc->nr_to_write--; -done: - if (ret) { + if (ret) btrfs_mark_ordered_io_finished(BTRFS_I(inode), folio, page_start, PAGE_SIZE, !ret); - mapping_set_error(folio->mapping, ret); - } +done: + if (ret < 0) + mapping_set_error(folio->mapping, ret); /* * Only unlock ranges that are submitted. As there can be some async * submitted ranges inside the folio. diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c4997200dbb2..d41bb47d59fb 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2305,7 +2305,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct folio *locked_fol out: if (ret < 0) - btrfs_cleanup_ordered_extents(inode, locked_folio, start, + btrfs_cleanup_ordered_extents(inode, NULL, start, end - start + 1); return ret; } -- 2.47.1

5 months, 4 weeks

3
3
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[PATCH] clk: clk-loongson2: Fix the number count of clk provider

by Binbin Zhou

Since commit 02fb4f008433 ("clk: clk-loongson2: Fix potential buffer overflow in flexible-array member access"), the clk provider register is failed. The count of `clks_num` is shown below: for (p = data; p->name; p++) clks_num++; In fact, `clks_num` represents the number of SoC clocks and should be expressed as the maximum value of the clock binding id in use (p->id + 1). Now we fix it to avoid the following error when trying to register a clk provider: [ 13.409595] of_clk_hw_onecell_get: invalid index 17 Fixes: 02fb4f008433 ("clk: clk-loongson2: Fix potential buffer overflow in flexible-array member access") Cc: stable(a)vger.kernel.org Signed-off-by: Binbin Zhou <zhoubinbin(a)loongson.cn> --- drivers/clk/clk-loongson2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/clk/clk-loongson2.c b/drivers/clk/clk-loongson2.c index 6bf51d5a49a1..b1b2038acd0b 100644 --- a/drivers/clk/clk-loongson2.c +++ b/drivers/clk/clk-loongson2.c @@ -294,7 +294,7 @@ static int loongson2_clk_probe(struct platform_device *pdev) return -EINVAL; for (p = data; p->name; p++) - clks_num++; + clks_num = max(clks_num, p->id + 1); clp = devm_kzalloc(dev, struct_size(clp, clk_data.hws, clks_num), GFP_KERNEL); -- 2.43.5

5 months, 4 weeks

3
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+ mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: zswap: properly synchronize freeing resources during CPU hotunplug has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Yosry Ahmed <yosryahmed(a)google.com> Subject: mm: zswap: properly synchronize freeing resources during CPU hotunplug Date: Wed, 8 Jan 2025 22:24:41 +0000 In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as some of the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead() (i.e. acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating and freeing resources with compression/decompression paths. Make sure that acomp_ctx.req is NULL when the resources are freed. In the compression/decompression paths, check if acomp_ctx.req is NULL after acquiring the mutex (meaning the CPU was offlined) and retry on the new CPU. The initialization of acomp_ctx.mutex is moved from the CPU hotplug callback to the pool initialization where it belongs (where the mutex is allocated). In addition to adding clarity, this makes sure that CPU hotplug cannot reinitialize a mutex that is already locked by compression/decompression. Previously a fix was attempted by holding cpus_read_lock() [1]. This would have caused a potential deadlock as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). A fix was also attempted using SRCU for synchronization, but Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug notifiers [2]. Alternative fixes that were considered/attempted and could have worked: - Refcounting the per-CPU acomp_ctx. This involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. - Disabling migration before getting the per-CPU acomp_ctx [3], but that's discouraged and is a much bigger hammer than needed, and could result in subtle performance issues. [1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/ [2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/ [3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/ Link: https://lkml.kernel.org/r/20250108222441.3622031-1-yosryahmed@google.com Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… Cc: Barry Song <baohua(a)kernel.org> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com> Cc: Nhat Pham <nphamcs(a)gmail.com> Cc: Vitaly Wool <vitalywool(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/zswap.c | 60 +++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 46 insertions(+), 14 deletions(-) --- a/mm/zswap.c~mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug +++ a/mm/zswap.c @@ -251,7 +251,7 @@ static struct zswap_pool *zswap_pool_cre struct zswap_pool *pool; char name[38]; /* 'zswap' + 32 char (max) num + \0 */ gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; - int ret; + int ret, cpu; if (!zswap_has_pool) { /* if either are unset, pool initialization failed, and we @@ -285,6 +285,9 @@ static struct zswap_pool *zswap_pool_cre goto error; } + for_each_possible_cpu(cpu) + mutex_init(&per_cpu_ptr(pool->acomp_ctx, cpu)->mutex); + ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); if (ret) @@ -821,11 +824,12 @@ static int zswap_cpu_comp_prepare(unsign struct acomp_req *req; int ret; - mutex_init(&acomp_ctx->mutex); - + mutex_lock(&acomp_ctx->mutex); acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); - if (!acomp_ctx->buffer) - return -ENOMEM; + if (!acomp_ctx->buffer) { + ret = -ENOMEM; + goto buffer_fail; + } acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); if (IS_ERR(acomp)) { @@ -844,6 +848,8 @@ static int zswap_cpu_comp_prepare(unsign ret = -ENOMEM; goto req_fail; } + + /* acomp_ctx->req must be NULL if the acomp_ctx is not fully initialized */ acomp_ctx->req = req; crypto_init_wait(&acomp_ctx->wait); @@ -855,12 +861,15 @@ static int zswap_cpu_comp_prepare(unsign acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &acomp_ctx->wait); + mutex_unlock(&acomp_ctx->mutex); return 0; req_fail: crypto_free_acomp(acomp_ctx->acomp); acomp_fail: kfree(acomp_ctx->buffer); +buffer_fail: + mutex_unlock(&acomp_ctx->mutex); return ret; } @@ -869,17 +878,45 @@ static int zswap_cpu_comp_dead(unsigned struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + mutex_lock(&acomp_ctx->mutex); if (!IS_ERR_OR_NULL(acomp_ctx)) { if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); + acomp_ctx->req = NULL; if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); kfree(acomp_ctx->buffer); } + mutex_unlock(&acomp_ctx->mutex); return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool) +{ + struct crypto_acomp_ctx *acomp_ctx; + + for (;;) { + acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); + mutex_lock(&acomp_ctx->mutex); + if (likely(acomp_ctx->req)) + return acomp_ctx; + /* + * It is possible that we were migrated to a different CPU after + * getting the per-CPU ctx but before the mutex was acquired. If + * the old CPU got offlined, zswap_cpu_comp_dead() could have + * already freed ctx->req (among other things) and set it to + * NULL. Just try again on the new CPU that we ended up on. + */ + mutex_unlock(&acomp_ctx->mutex); + } +} + +static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *acomp_ctx) +{ + mutex_unlock(&acomp_ctx->mutex); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,10 +930,7 @@ static bool zswap_compress(struct page * gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(pool); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); @@ -949,7 +983,7 @@ unlock: else if (alloc_ret) zswap_reject_alloc_fail++; - mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_unlock(acomp_ctx); return comp_ret == 0 && alloc_ret == 0; } @@ -960,9 +994,7 @@ static void zswap_decompress(struct zswa struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer @@ -986,10 +1018,10 @@ static void zswap_decompress(struct zswa acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); - mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_unlock(acomp_ctx); } /********************************* _ Patches currently in -mm which might be from yosryahmed(a)google.com are revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug.patch mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug-fix.patch

5 months, 4 weeks

1
0
0 0

[PATCH v2] mm: zswap: properly synchronize freeing resources during CPU hotunplug

by Yosry Ahmed

In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as some of the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead() (i.e. acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating and freeing resources with compression/decompression paths. Make sure that acomp_ctx.req is NULL when the resources are freed. In the compression/decompression paths, check if acomp_ctx.req is NULL after acquiring the mutex (meaning the CPU was offlined) and retry on the new CPU. The initialization of acomp_ctx.mutex is moved from the CPU hotplug callback to the pool initialization where it belongs (where the mutex is allocated). In addition to adding clarity, this makes sure that CPU hotplug cannot reinitialize a mutex that is already locked by compression/decompression. Previously a fix was attempted by holding cpus_read_lock() [1]. This would have caused a potential deadlock as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). A fix was also attempted using SRCU for synchronization, but Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug notifiers [2]. Alternative fixes that were considered/attempted and could have worked: - Refcounting the per-CPU acomp_ctx. This involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. - Disabling migration before getting the per-CPU acomp_ctx [3], but that's discouraged and is a much bigger hammer than needed, and could result in subtle performance issues. [1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/ [2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/ [3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/ Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Cc: <stable(a)vger.kernel.org> Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… --- This applies on top of the latest mm-hotfixes-unstable on top of 'Revert "mm: zswap: fix race between [de]compression and CPU hotunplug"' and after 'mm: zswap: disable migration while using per-CPU acomp_ctx' was dropped. v1 -> v2: - Move the initialization of the mutex to pool initialization. - Use the mutex to also synchronize with the CPU hotplug callback (i.e. zswap_cpu_comp_prep()). - Naming cleanups. --- mm/zswap.c | 60 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 46 insertions(+), 14 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index f6316b66fb236..4d7e564732267 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -251,7 +251,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor) struct zswap_pool *pool; char name[38]; /* 'zswap' + 32 char (max) num + \0 */ gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; - int ret; + int ret, cpu; if (!zswap_has_pool) { /* if either are unset, pool initialization failed, and we @@ -285,6 +285,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor) goto error; } + for_each_possible_cpu(cpu) + mutex_init(&per_cpu_ptr(pool->acomp_ctx, cpu)->mutex); + ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); if (ret) @@ -821,11 +824,12 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) struct acomp_req *req; int ret; - mutex_init(&acomp_ctx->mutex); - + mutex_lock(&acomp_ctx->mutex); acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); - if (!acomp_ctx->buffer) - return -ENOMEM; + if (!acomp_ctx->buffer) { + ret = -ENOMEM; + goto buffer_fail; + } acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); if (IS_ERR(acomp)) { @@ -844,6 +848,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) ret = -ENOMEM; goto req_fail; } + + /* acomp_ctx->req must be NULL if the acomp_ctx is not fully initialized */ acomp_ctx->req = req; crypto_init_wait(&acomp_ctx->wait); @@ -855,12 +861,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &acomp_ctx->wait); + mutex_unlock(&acomp_ctx->mutex); return 0; req_fail: crypto_free_acomp(acomp_ctx->acomp); acomp_fail: kfree(acomp_ctx->buffer); +buffer_fail: + mutex_unlock(&acomp_ctx->mutex); return ret; } @@ -869,17 +878,45 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + mutex_lock(&acomp_ctx->mutex); if (!IS_ERR_OR_NULL(acomp_ctx)) { if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); + acomp_ctx->req = NULL; if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); kfree(acomp_ctx->buffer); } + mutex_unlock(&acomp_ctx->mutex); return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool) +{ + struct crypto_acomp_ctx *acomp_ctx; + + for (;;) { + acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); + mutex_lock(&acomp_ctx->mutex); + if (likely(acomp_ctx->req)) + return acomp_ctx; + /* + * It is possible that we were migrated to a different CPU after + * getting the per-CPU ctx but before the mutex was acquired. If + * the old CPU got offlined, zswap_cpu_comp_dead() could have + * already freed ctx->req (among other things) and set it to + * NULL. Just try again on the new CPU that we ended up on. + */ + mutex_unlock(&acomp_ctx->mutex); + } +} + +static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *acomp_ctx) +{ + mutex_unlock(&acomp_ctx->mutex); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,10 +930,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(pool); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); @@ -949,7 +983,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, else if (alloc_ret) zswap_reject_alloc_fail++; - mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_unlock(acomp_ctx); return comp_ret == 0 && alloc_ret == 0; } @@ -960,9 +994,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer @@ -986,10 +1018,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); - mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_unlock(acomp_ctx); } /********************************* -- 2.47.1.613.gc27f4b7a9f-goog

5 months, 4 weeks

2
2
0 0

[PATCH] mm: zswap: properly synchronize freeing resources during CPU hotunplug

by Yosry Ahmed

In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as some of the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead(). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. During CPU hotunplug, hold the acomp_ctx.mutex before freeing any resources, and set acomp_ctx.req to NULL when it is freed. In the compress/decompress paths, after acquiring the acomp_ctx.mutex make sure that acomp_ctx.req is not NULL (i.e. acomp_ctx resources were not freed by CPU hotunplug). Otherwise, retry with the acomp_ctx from the new CPU. This adds proper synchronization to ensure that the acomp_ctx resources are not freed from under compress/decompress paths. Note that the per-CPU acomp_ctx itself (including the mutex) is not freed during CPU hotunplug, only acomp_ctx.req, acomp_ctx.buffer, and acomp_ctx.acomp. So it is safe to acquire the acomp_ctx.mutex of a CPU after it is hotunplugged. Previously a fix was attempted by holding cpus_read_lock() [1]. This would have caused a potential deadlock as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). A fix was also attempted using SRCU for synchronization, but Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug notifiers [2]. Alternative fixes that were considered/attempted and could have worked: - Refcounting the per-CPU acomp_ctx. This involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. - Disabling migration before getting the per-CPU acomp_ctx [3], but that's discouraged and is a much bigger hammer than needed, and could result in subtle performance issues. [1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/ [2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/ [3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/ Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Cc: <stable(a)vger.kernel.org> Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… --- This applies on top of the latest mm-hotfixes-unstable on top of 'Revert "mm: zswap: fix race between [de]compression and CPU hotunplug"' and after 'mm: zswap: disable migration while using per-CPU acomp_ctx' was dropped. --- mm/zswap.c | 42 +++++++++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 9 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index f6316b66fb236..4e3148050e093 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -869,17 +869,46 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + mutex_lock(&acomp_ctx->mutex); if (!IS_ERR_OR_NULL(acomp_ctx)) { if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); + acomp_ctx->req = NULL; if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); kfree(acomp_ctx->buffer); } + mutex_unlock(&acomp_ctx->mutex); return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock( + struct crypto_acomp_ctx __percpu *acomp_ctx) +{ + struct crypto_acomp_ctx *ctx; + + for (;;) { + ctx = raw_cpu_ptr(acomp_ctx); + mutex_lock(&ctx->mutex); + if (likely(ctx->req)) + return ctx; + /* + * It is possible that we were migrated to a different CPU after + * getting the per-CPU ctx but before the mutex was acquired. If + * the old CPU got offlined, zswap_cpu_comp_dead() could have + * already freed ctx->req (among other things) and set it to + * NULL. Just try again on the new CPU that we ended up on. + */ + mutex_unlock(&ctx->mutex); + } +} + +static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *ctx) +{ + mutex_unlock(&ctx->mutex); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,10 +922,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(pool->acomp_ctx); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); @@ -949,7 +975,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, else if (alloc_ret) zswap_reject_alloc_fail++; - mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_unlock(acomp_ctx); return comp_ret == 0 && alloc_ret == 0; } @@ -960,9 +986,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool->acomp_ctx); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer @@ -986,10 +1010,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); - mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_unlock(acomp_ctx); } /********************************* -- 2.47.1.613.gc27f4b7a9f-goog

5 months, 4 weeks

3
3
0 0

[PATCH 6.6.y 1/2] erofs: handle overlapped pclusters out of crafted images properly

by Gao Xiang

commit 9e2f9d34dd12e6e5b244ec488bcebd0c2d566c50 upstream. syzbot reported a task hang issue due to a deadlock case where it is waiting for the folio lock of a cached folio that will be used for cache I/Os. After looking into the crafted fuzzed image, I found it's formed with several overlapped big pclusters as below: Ext: logical offset | length : physical offset | length 0: 0.. 16384 | 16384 : 151552.. 167936 | 16384 1: 16384.. 32768 | 16384 : 155648.. 172032 | 16384 2: 32768.. 49152 | 16384 : 537223168.. 537239552 | 16384 ... Here, extent 0/1 are physically overlapped although it's entirely _impossible_ for normal filesystem images generated by mkfs. First, managed folios containing compressed data will be marked as up-to-date and then unlocked immediately (unlike in-place folios) when compressed I/Os are complete. If physical blocks are not submitted in the incremental order, there should be separate BIOs to avoid dependency issues. However, the current code mis-arranges z_erofs_fill_bio_vec() and BIO submission which causes unexpected BIO waits. Second, managed folios will be connected to their own pclusters for efficient inter-queries. However, this is somewhat hard to implement easily if overlapped big pclusters exist. Again, these only appear in fuzzed images so let's simply fall back to temporary short-lived pages for correctness. Additionally, it justifies that referenced managed folios cannot be truncated for now and reverts part of commit 2080ca1ed3e4 ("erofs: tidy up `struct z_erofs_bvec`") for simplicity although it shouldn't be any difference. Reported-by: syzbot+4fc98ed414ae63d1ada2(a)syzkaller.appspotmail.com Reported-by: syzbot+de04e06b28cfecf2281c(a)syzkaller.appspotmail.com Reported-by: syzbot+c8c8238b394be4a1087d(a)syzkaller.appspotmail.com Tested-by: syzbot+4fc98ed414ae63d1ada2(a)syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/0000000000002fda01061e334873@google.com Fixes: 8e6c8fa9f2e9 ("erofs: enable big pcluster feature") Link: https://lore.kernel.org/r/20240910070847.3356592-1-hsiangkao@linux.alibaba.… Signed-off-by: Gao Xiang <hsiangkao(a)linux.alibaba.com> --- fs/erofs/zdata.c | 59 +++++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 28 deletions(-) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 1c0e6167d8e7..9fa07436a4da 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -1483,14 +1483,13 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl, goto out; lock_page(page); - - /* only true if page reclaim goes wrong, should never happen */ - DBG_BUGON(justfound && PagePrivate(page)); - - /* the page is still in manage cache */ - if (page->mapping == mc) { + if (likely(page->mapping == mc)) { WRITE_ONCE(pcl->compressed_bvecs[nr].page, page); + /* + * The cached folio is still in managed cache but without + * a valid `->private` pcluster hint. Let's reconnect them. + */ if (!PagePrivate(page)) { /* * impossible to be !PagePrivate(page) for @@ -1504,22 +1503,24 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl, SetPagePrivate(page); } - /* no need to submit io if it is already up-to-date */ - if (PageUptodate(page)) { - unlock_page(page); - page = NULL; + if (likely(page->private == (unsigned long)pcl)) { + /* don't submit cache I/Os again if already uptodate */ + if (PageUptodate(page)) { + unlock_page(page); + page = NULL; + + } + goto out; } - goto out; + /* + * Already linked with another pcluster, which only appears in + * crafted images by fuzzers for now. But handle this anyway. + */ + tocache = false; /* use temporary short-lived pages */ + } else { + DBG_BUGON(1); /* referenced managed folios can't be truncated */ + tocache = true; } - - /* - * the managed page has been truncated, it's unsafe to - * reuse this one, let's allocate a new cache-managed page. - */ - DBG_BUGON(page->mapping); - DBG_BUGON(!justfound); - - tocache = true; unlock_page(page); put_page(page); out_allocpage: @@ -1677,16 +1678,11 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, end = cur + pcl->pclusterpages; do { - struct page *page; - - page = pickup_page_for_submission(pcl, i++, - &f->pagepool, mc); - if (!page) - continue; + struct page *page = NULL; if (bio && (cur != last_index + 1 || last_bdev != mdev.m_bdev)) { -submit_bio_retry: +drain_io: submit_bio(bio); if (memstall) { psi_memstall_leave(&pflags); @@ -1695,6 +1691,13 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, bio = NULL; } + if (!page) { + page = pickup_page_for_submission(pcl, i++, + &f->pagepool, mc); + if (!page) + continue; + } + if (unlikely(PageWorkingset(page)) && !memstall) { psi_memstall_enter(&pflags); memstall = 1; @@ -1715,7 +1718,7 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, } if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) - goto submit_bio_retry; + goto drain_io; last_index = cur; bypass = false; -- 2.43.5

5 months, 4 weeks

2
2
0 0

[PATCH 5.10-6.1] ceph: give up on paths longer than PATH_MAX

by Ilya Dryomov

From: Max Kellermann <max.kellermann(a)ionos.com> commit 550f7ca98ee028a606aa75705a7e77b1bd11720f upstream. If the full path to be built by ceph_mdsc_build_path() happens to be longer than PATH_MAX, then this function will enter an endless (retry) loop, effectively blocking the whole task. Most of the machine becomes unusable, making this a very simple and effective DoS vulnerability. I cannot imagine why this retry was ever implemented, but it seems rather useless and harmful to me. Let's remove it and fail with ENAMETOOLONG instead. Cc: stable(a)vger.kernel.org Reported-by: Dario Weißer <dario(a)cure53.de> Signed-off-by: Max Kellermann <max.kellermann(a)ionos.com> Reviewed-by: Alex Markuze <amarkuze(a)redhat.com> Signed-off-by: Ilya Dryomov <idryomov(a)gmail.com> [idryomov(a)gmail.com: backport to 6.1: pr_warn() is still in use] --- fs/ceph/mds_client.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index da9fcf48ab6c..741ca7d10032 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2447,12 +2447,11 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, if (pos < 0) { /* - * A rename didn't occur, but somehow we didn't end up where - * we thought we would. Throw a warning and try again. + * The path is longer than PATH_MAX and this function + * cannot ever succeed. Creating paths that long is + * possible with Ceph, but Linux cannot use them. */ - pr_warn("build_path did not end path lookup where " - "expected, pos is %d\n", pos); - goto retry; + return ERR_PTR(-ENAMETOOLONG); } *pbase = base; -- 2.46.1

5 months, 4 weeks

2
1
0 0

[PATCH net] netdev: prevent accessing NAPI instances from another namespace

by Jakub Kicinski

The NAPI IDs were not fully exposed to user space prior to the netlink API, so they were never namespaced. The netlink API must ensure that at the very least NAPI instance belongs to the same netns as the owner of the genl sock. napi_by_id() can become static now, but it needs to move because of dev_get_by_napi_id(). Cc: stable(a)vger.kernel.org Fixes: 1287c1ae0fc2 ("netdev-genl: Support setting per-NAPI config values") Fixes: 27f91aaf49b3 ("netdev-genl: Add netlink framework functions for napi") Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> --- Splitting this into fix per-version is a bit tricky, because we need to replace the napi_by_id() helper with a better one. I'll send the stable versions manually. CC: jdamato(a)fastly.com CC: almasrymina(a)google.com CC: amritha.nambiar(a)intel.com CC: sridhar.samudrala(a)intel.com --- net/core/dev.c | 43 +++++++++++++++++++++++++++++------------- net/core/dev.h | 3 ++- net/core/netdev-genl.c | 6 ++---- 3 files changed, 34 insertions(+), 18 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 7c63d97b13c1..e001df4cb486 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -753,6 +753,36 @@ int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr, } EXPORT_SYMBOL_GPL(dev_fill_forward_path); +/* must be called under rcu_read_lock(), as we dont take a reference */ +static struct napi_struct *napi_by_id(unsigned int napi_id) +{ + unsigned int hash = napi_id % HASH_SIZE(napi_hash); + struct napi_struct *napi; + + hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node) + if (napi->napi_id == napi_id) + return napi; + + return NULL; +} + +/* must be called under rcu_read_lock(), as we dont take a reference */ +struct napi_struct *netdev_napi_by_id(struct net *net, unsigned int napi_id) +{ + struct napi_struct *napi; + + napi = napi_by_id(napi_id); + if (!napi) + return NULL; + + if (WARN_ON_ONCE(!napi->dev)) + return NULL; + if (!net_eq(net, dev_net(napi->dev))) + return NULL; + + return napi; +} + /** * __dev_get_by_name - find a device by its name * @net: the applicable net namespace @@ -6293,19 +6323,6 @@ bool napi_complete_done(struct napi_struct *n, int work_done) } EXPORT_SYMBOL(napi_complete_done); -/* must be called under rcu_read_lock(), as we dont take a reference */ -struct napi_struct *napi_by_id(unsigned int napi_id) -{ - unsigned int hash = napi_id % HASH_SIZE(napi_hash); - struct napi_struct *napi; - - hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node) - if (napi->napi_id == napi_id) - return napi; - - return NULL; -} - static void skb_defer_free_flush(struct softnet_data *sd) { struct sk_buff *skb, *next; diff --git a/net/core/dev.h b/net/core/dev.h index aa91eed55a40..08812a025a9b 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -22,6 +22,8 @@ struct sd_flow_limit { extern int netdev_flow_limit_table_len; +struct napi_struct *netdev_napi_by_id(struct net *net, unsigned int napi_id); + #ifdef CONFIG_PROC_FS int __init dev_proc_init(void); #else @@ -269,7 +271,6 @@ void xdp_do_check_flushed(struct napi_struct *napi); static inline void xdp_do_check_flushed(struct napi_struct *napi) { } #endif -struct napi_struct *napi_by_id(unsigned int napi_id); void kick_defer_list_purge(struct softnet_data *sd, unsigned int cpu); #define XMIT_RECURSION_LIMIT 8 diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c index 125b660004d3..a3bdaf075b6b 100644 --- a/net/core/netdev-genl.c +++ b/net/core/netdev-genl.c @@ -167,8 +167,6 @@ netdev_nl_napi_fill_one(struct sk_buff *rsp, struct napi_struct *napi, void *hdr; pid_t pid; - if (WARN_ON_ONCE(!napi->dev)) - return -EINVAL; if (!(napi->dev->flags & IFF_UP)) return 0; @@ -234,7 +232,7 @@ int netdev_nl_napi_get_doit(struct sk_buff *skb, struct genl_info *info) rtnl_lock(); rcu_read_lock(); - napi = napi_by_id(napi_id); + napi = netdev_napi_by_id(genl_info_net(info), napi_id); if (napi) { err = netdev_nl_napi_fill_one(rsp, napi, info); } else { @@ -355,7 +353,7 @@ int netdev_nl_napi_set_doit(struct sk_buff *skb, struct genl_info *info) rtnl_lock(); rcu_read_lock(); - napi = napi_by_id(napi_id); + napi = netdev_napi_by_id(genl_info_net(info), napi_id); if (napi) { err = netdev_nl_napi_set_config(napi, info); } else { -- 2.47.1

5 months, 4 weeks

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[PATCH v5 0/5] arm64: Support 2024 dpISA extensions

by Mark Brown

The 2024 architecture release includes a number of data processing extensions, mostly SVE and SME additions with a few others. These are all very straightforward extensions which add instructions but no architectural state so only need hwcaps and exposing of the ID registers to KVM guests and userspace. Signed-off-by: Mark Brown <broonie(a)kernel.org> --- Changes in v5: - Rebase onto arm64/for-next/cpufeature, which incorporates most of the sysreg updates from earlier versions. - Remove SF8MM8 and SF8MM4 register defintitions which were removed from the ISA in the 2024-12 XML release, along with their associated hwcaps. - Incorporate Marc's fix for SVE hwcaps on SME only systems and update the hwcaps for the newly added features to follow the same pattern. - Link to v4: https://lore.kernel.org/r/20241211-arm64-2024-dpisa-v4-0-0fd403876df2@kerne… Changes in v4: - Fix encodings for ID_AA64ISAR3_EL1. - Link to v3: https://lore.kernel.org/r/20241203-arm64-2024-dpisa-v3-0-a6c78b1aa297@kerne… Changes in v3: - Commit log update for the hwcap test. - Link to v2: https://lore.kernel.org/r/20241030-arm64-2024-dpisa-v2-0-b6601a15d2a5@kerne… Changes in v2: - Filter KVM guest visible bitfields in ID_AA64ISAR3_EL1 to only those we make writeable. - Link to v1: https://lore.kernel.org/r/20241028-arm64-2024-dpisa-v1-0-a38d08b008a8@kerne… --- Marc Zyngier (1): arm64: Filter out SVE hwcaps when FEAT_SVE isn't implemented Mark Brown (4): arm64/sysreg: Update ID_AA64SMFR0_EL1 to DDI0601 2024-12 arm64/hwcap: Describe 2024 dpISA extensions to userspace KVM: arm64: Allow control of dpISA extensions in ID_AA64ISAR3_EL1 kselftest/arm64: Add 2024 dpISA extensions to hwcap test Documentation/arch/arm64/elf_hwcaps.rst | 89 +++++++++-- arch/arm64/include/asm/hwcap.h | 15 ++ arch/arm64/include/uapi/asm/hwcap.h | 15 ++ arch/arm64/kernel/cpufeature.c | 71 +++++++-- arch/arm64/kernel/cpuinfo.c | 15 ++ arch/arm64/kvm/sys_regs.c | 6 +- arch/arm64/tools/sysreg | 26 +++- tools/testing/selftests/arm64/abi/hwcap.c | 235 +++++++++++++++++++++++++++++- 8 files changed, 441 insertions(+), 31 deletions(-) --- base-commit: d66e21d59ed0e043e68ef8c6541c1e9f1a962614 change-id: 20241008-arm64-2024-dpisa-8091074a7f48 Best regards, -- Mark Brown <broonie(a)kernel.org>

5 months, 4 weeks

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[PATCH v3] arm64/sme: Move storage of reg_smidr to __cpuinfo_store_cpu()

by Mark Brown

In commit 892f7237b3ff ("arm64: Delay initialisation of cpuinfo_arm64::reg_{zcr,smcr}") we moved access to ZCR, SMCR and SMIDR later in the boot process in order to ensure that we don't attempt to interact with them if SVE or SME is disabled on the command line. Unfortunately when initialising the boot CPU in init_cpu_features() we work on a copy of the struct cpuinfo_arm64 for the boot CPU used only during boot, not the percpu copy used by the sysfs code. The expectation of the feature identification code was that the ID registers would be read in __cpuinfo_store_cpu() and the values not modified by init_cpu_features(). The main reason for the original change was to avoid early accesses to ZCR on practical systems that were seen shipping with SVE reported in ID registers but traps enabled at EL3 and handled as fatal errors, SME was rolled in due to the similarity with SVE. Since then we have removed the early accesses to ZCR and SMCR in commits: abef0695f9665c3d ("arm64/sve: Remove ZCR pseudo register from cpufeature code") 391208485c3ad50f ("arm64/sve: Remove SMCR pseudo register from cpufeature code") so only the SMIDR_EL1 part of the change remains. Since SMIDR_EL1 is only trapped via FEAT_IDST and not the SME trap it is less likely to be affected by similar issues, and the factors that lead to issues with SVE are less likely to apply to SME. Since we have not yet seen practical SME systems that need to use a command line override (and are only just beginning to see SME systems at all) and the ID register read is much more likely to be safe let's just store SMIDR_EL1 along with all the other ID register reads in __cpuinfo_store_cpu(). This issue wasn't apparent when testing on emulated platforms that do not report values in SMIDR_EL1. Fixes: 892f7237b3ff ("arm64: Delay initialisation of cpuinfo_arm64::reg_{zcr,smcr}") Signed-off-by: Mark Brown <broonie(a)kernel.org> Cc: stable(a)vger.kernel.org --- Changes in v3: - Leave the override in place. - Link to v2: https://lore.kernel.org/r/20241216-arm64-fix-boot-cpu-smidr-v2-1-a99ffba2c3… Changes in v2: - Move the ID register read back to __cpuinfo_store_cpu(). - Remove the command line option for SME ID register override. - Link to v1: https://lore.kernel.org/r/20241214-arm64-fix-boot-cpu-smidr-v1-1-0745c40772… --- arch/arm64/kernel/cpufeature.c | 13 ------------- arch/arm64/kernel/cpuinfo.c | 10 ++++++++++ 2 files changed, 10 insertions(+), 13 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6ce71f444ed84f9056196bb21bbfac61c9687e30..818aca922ca6066eb4bdf79e153cccb24246c61b 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1167,12 +1167,6 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info) id_aa64pfr1_sme(read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1))) { unsigned long cpacr = cpacr_save_enable_kernel_sme(); - /* - * We mask out SMPS since even if the hardware - * supports priorities the kernel does not at present - * and we block access to them. - */ - info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS; vec_init_vq_map(ARM64_VEC_SME); cpacr_restore(cpacr); @@ -1423,13 +1417,6 @@ void update_cpu_features(int cpu, id_aa64pfr1_sme(read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1))) { unsigned long cpacr = cpacr_save_enable_kernel_sme(); - /* - * We mask out SMPS since even if the hardware - * supports priorities the kernel does not at present - * and we block access to them. - */ - info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS; - /* Probe vector lengths */ if (!system_capabilities_finalized()) vec_update_vq_map(ARM64_VEC_SME); diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index d79e88fccdfce427507e7a34c5959ce6309cbd12..c45633b5ae233fe78607fce3d623efb28a9f341a 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -482,6 +482,16 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info) if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0)) info->reg_mpamidr = read_cpuid(MPAMIDR_EL1); + if (IS_ENABLED(CONFIG_ARM64_SME) && + id_aa64pfr1_sme(info->reg_id_aa64pfr1)) { + /* + * We mask out SMPS since even if the hardware + * supports priorities the kernel does not at present + * and we block access to them. + */ + info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS; + } + cpuinfo_detect_icache_policy(info); } --- base-commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4 change-id: 20241213-arm64-fix-boot-cpu-smidr-386b8db292b2 Best regards, -- Mark Brown <broonie(a)kernel.org>

5 months, 4 weeks

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Linux-stable-mirror January 2025