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[PATCH] x86/boot/compressed/64: clear high flags from pgd entry in configure_5level_paging

by Eric Hagberg

In commit d0ceea662d45 ("x86/mm: Add _PAGE_NOPTISHADOW bit to avoid updating userspace page tables") we started setting _PAGE_NOPTISHADOW (bit 58) in identity map PTEs created by kernel_ident_mapping_init. In configure_5level_paging when transiting from 5-level paging to 4-level paging we copy the first p4d to become our new (4-level) pgd by dereferencing the first entry in the current pgd, but we only mask off the low 12 bits in the pgd entry. When kexecing, the previous kernel sets up an identity map using kernel_ident_mapping_init before transiting to the new kernel, which means the new kernel gets a pgd with entries with bit 58 set. Then we mask off only the low 12 bits, resulting in a non-canonical address, and try to copy from it, and fault. Fixes: d0ceea662d45 ("x86/mm: Add _PAGE_NOPTISHADOW bit to avoid updating userspace page tables") Signed-off-by: Eric Hagberg <ehagberg(a)janestreet.com> Cc: stable(a)vger.kernel.org --- arch/x86/boot/compressed/pgtable_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index bdd26050dff7..c785c5d54a11 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -180,7 +180,7 @@ asmlinkage void configure_5level_paging(struct boot_params *bp, void *pgtable) * We cannot just point to the page table from trampoline as it * may be above 4G. */ - src = *(unsigned long *)__native_read_cr3() & PAGE_MASK; + src = *(unsigned long *)__native_read_cr3() & PTE_PFN_MASK; memcpy(trampoline_32bit, (void *)src, PAGE_SIZE); } -- 2.43.7

3 months, 1 week

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Crypto Loan Pre-Approval

by Lucy Seinfield

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3 months, 1 week

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[PATCH v2] bus: mhi: ep: Fix chained transfer handling in read path

by Sumit Kumar

From: Sumit Kumar <sumk(a)qti.qualcomm.com> The current implementation of mhi_ep_read_channel, in case of chained transactions, assumes the End of Transfer(EOT) bit is received with the doorbell. As a result, it may incorrectly advance mhi_chan->rd_offset beyond wr_offset during host-to-device transfers when EOT has not yet arrived. This can lead to access of unmapped host memory, causing IOMMU faults and processing of stale TREs. This change modifies the loop condition to ensure mhi_queue is not empty, allowing the function to process only valid TREs up to the current write pointer. This prevents premature reads and ensures safe traversal of chained TREs. Removed buf_left from the while loop condition to avoid exiting prematurely before reading the ring completely. Removed write_offset since it will always be zero because the new cache buffer is allocated everytime. Fixes: 5301258899773 ("bus: mhi: ep: Add support for reading from the host") Cc: stable(a)vger.kernel.org Co-developed-by: Akhil Vinod <akhvin(a)qti.qualcomm.com> Signed-off-by: Akhil Vinod <akhvin(a)qti.qualcomm.com> Signed-off-by: Sumit Kumar <sumk(a)qti.qualcomm.com> --- Changes in v2: - Use mhi_ep_queue_is_empty in while loop (Mani). - Remove do while loop in mhi_ep_process_ch_ring (Mani). - Remove buf_left, wr_offset, tr_done. - Haven't added Reviewed-by as there is change in logic. - Link to v1: https://lore.kernel.org/r/20250709-chained_transfer-v1-1-2326a4605c9c@quici… --- drivers/bus/mhi/ep/main.c | 37 ++++++++++++------------------------- 1 file changed, 12 insertions(+), 25 deletions(-) diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c index b3eafcf2a2c50d95e3efd3afb27038ecf55552a5..cdea24e9291959ae0a92487c1b9698dc8164d2f1 100644 --- a/drivers/bus/mhi/ep/main.c +++ b/drivers/bus/mhi/ep/main.c @@ -403,17 +403,13 @@ static int mhi_ep_read_channel(struct mhi_ep_cntrl *mhi_cntrl, { struct mhi_ep_chan *mhi_chan = &mhi_cntrl->mhi_chan[ring->ch_id]; struct device *dev = &mhi_cntrl->mhi_dev->dev; - size_t tr_len, read_offset, write_offset; + size_t tr_len, read_offset; struct mhi_ep_buf_info buf_info = {}; u32 len = MHI_EP_DEFAULT_MTU; struct mhi_ring_element *el; - bool tr_done = false; void *buf_addr; - u32 buf_left; int ret; - buf_left = len; - do { /* Don't process the transfer ring if the channel is not in RUNNING state */ if (mhi_chan->state != MHI_CH_STATE_RUNNING) { @@ -426,24 +422,23 @@ static int mhi_ep_read_channel(struct mhi_ep_cntrl *mhi_cntrl, /* Check if there is data pending to be read from previous read operation */ if (mhi_chan->tre_bytes_left) { dev_dbg(dev, "TRE bytes remaining: %u\n", mhi_chan->tre_bytes_left); - tr_len = min(buf_left, mhi_chan->tre_bytes_left); + tr_len = min(len, mhi_chan->tre_bytes_left); } else { mhi_chan->tre_loc = MHI_TRE_DATA_GET_PTR(el); mhi_chan->tre_size = MHI_TRE_DATA_GET_LEN(el); mhi_chan->tre_bytes_left = mhi_chan->tre_size; - tr_len = min(buf_left, mhi_chan->tre_size); + tr_len = min(len, mhi_chan->tre_size); } read_offset = mhi_chan->tre_size - mhi_chan->tre_bytes_left; - write_offset = len - buf_left; buf_addr = kmem_cache_zalloc(mhi_cntrl->tre_buf_cache, GFP_KERNEL); if (!buf_addr) return -ENOMEM; buf_info.host_addr = mhi_chan->tre_loc + read_offset; - buf_info.dev_addr = buf_addr + write_offset; + buf_info.dev_addr = buf_addr; buf_info.size = tr_len; buf_info.cb = mhi_ep_read_completion; buf_info.cb_buf = buf_addr; @@ -459,16 +454,12 @@ static int mhi_ep_read_channel(struct mhi_ep_cntrl *mhi_cntrl, goto err_free_buf_addr; } - buf_left -= tr_len; mhi_chan->tre_bytes_left -= tr_len; - if (!mhi_chan->tre_bytes_left) { - if (MHI_TRE_DATA_GET_IEOT(el)) - tr_done = true; - + if (!mhi_chan->tre_bytes_left) mhi_chan->rd_offset = (mhi_chan->rd_offset + 1) % ring->ring_size; - } - } while (buf_left && !tr_done); + /* Read until the some buffer is left or the ring becomes not empty */ + } while (!mhi_ep_queue_is_empty(mhi_chan->mhi_dev, DMA_TO_DEVICE)); return 0; @@ -502,15 +493,11 @@ static int mhi_ep_process_ch_ring(struct mhi_ep_ring *ring) mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result); } else { /* UL channel */ - do { - ret = mhi_ep_read_channel(mhi_cntrl, ring); - if (ret < 0) { - dev_err(&mhi_chan->mhi_dev->dev, "Failed to read channel\n"); - return ret; - } - - /* Read until the ring becomes empty */ - } while (!mhi_ep_queue_is_empty(mhi_chan->mhi_dev, DMA_TO_DEVICE)); + ret = mhi_ep_read_channel(mhi_cntrl, ring); + if (ret < 0) { + dev_err(&mhi_chan->mhi_dev->dev, "Failed to read channel\n"); + return ret; + } } return 0; --- base-commit: 4c06e63b92038fadb566b652ec3ec04e228931e8 change-id: 20250709-chained_transfer-0b95f8afa487 Best regards, -- Sumit Kumar <quic_sumk(a)quicinc.com>

3 months, 1 week

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[PATCH] mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()

by Uladzislau Rezki (Sony)

kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and always allocate memory using the hardcoded GFP_KERNEL flag. This makes them inconsistent with vmalloc(), which was recently extended to support GFP_NOFS and GFP_NOIO allocations. Page table allocations performed during shadow population also ignore the external gfp_mask. To preserve the intended semantics of GFP_NOFS and GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate memalloc scope. This patch: - Extends kasan_populate_vmalloc() and helpers to take gfp_mask; - Passes gfp_mask down to alloc_pages_bulk() and __get_free_page(); - Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore() around apply_to_page_range(); - Updates vmalloc.c and percpu allocator call sites accordingly. To: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Cc: <stable(a)vger.kernel.org> Fixes: 451769ebb7e7 ("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc") Signed-off-by: Uladzislau Rezki (Sony) <urezki(a)gmail.com> --- include/linux/kasan.h | 6 +++--- mm/kasan/shadow.c | 31 ++++++++++++++++++++++++------- mm/vmalloc.c | 8 ++++---- 3 files changed, 31 insertions(+), 14 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 890011071f2b..fe5ce9215821 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -562,7 +562,7 @@ static inline void kasan_init_hw_tags(void) { } #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) void kasan_populate_early_vm_area_shadow(void *start, unsigned long size); -int kasan_populate_vmalloc(unsigned long addr, unsigned long size); +int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask); void kasan_release_vmalloc(unsigned long start, unsigned long end, unsigned long free_region_start, unsigned long free_region_end, @@ -574,7 +574,7 @@ static inline void kasan_populate_early_vm_area_shadow(void *start, unsigned long size) { } static inline int kasan_populate_vmalloc(unsigned long start, - unsigned long size) + unsigned long size, gfp_t gfp_mask) { return 0; } @@ -610,7 +610,7 @@ static __always_inline void kasan_poison_vmalloc(const void *start, static inline void kasan_populate_early_vm_area_shadow(void *start, unsigned long size) { } static inline int kasan_populate_vmalloc(unsigned long start, - unsigned long size) + unsigned long size, gfp_t gfp_mask) { return 0; } diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index d2c70cd2afb1..c7c0be119173 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -335,13 +335,13 @@ static void ___free_pages_bulk(struct page **pages, int nr_pages) } } -static int ___alloc_pages_bulk(struct page **pages, int nr_pages) +static int ___alloc_pages_bulk(struct page **pages, int nr_pages, gfp_t gfp_mask) { unsigned long nr_populated, nr_total = nr_pages; struct page **page_array = pages; while (nr_pages) { - nr_populated = alloc_pages_bulk(GFP_KERNEL, nr_pages, pages); + nr_populated = alloc_pages_bulk(gfp_mask, nr_pages, pages); if (!nr_populated) { ___free_pages_bulk(page_array, nr_total - nr_pages); return -ENOMEM; @@ -353,25 +353,42 @@ static int ___alloc_pages_bulk(struct page **pages, int nr_pages) return 0; } -static int __kasan_populate_vmalloc(unsigned long start, unsigned long end) +static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_t gfp_mask) { unsigned long nr_pages, nr_total = PFN_UP(end - start); struct vmalloc_populate_data data; + unsigned int flags; int ret = 0; - data.pages = (struct page **)__get_free_page(GFP_KERNEL | __GFP_ZERO); + data.pages = (struct page **)__get_free_page(gfp_mask | __GFP_ZERO); if (!data.pages) return -ENOMEM; while (nr_total) { nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0])); - ret = ___alloc_pages_bulk(data.pages, nr_pages); + ret = ___alloc_pages_bulk(data.pages, nr_pages, gfp_mask); if (ret) break; data.start = start; + + /* + * page tables allocations ignore external gfp mask, enforce it + * by the scope API + */ + if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO) + flags = memalloc_nofs_save(); + else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0) + flags = memalloc_noio_save(); + ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE, kasan_populate_vmalloc_pte, &data); + + if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO) + memalloc_nofs_restore(flags); + else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0) + memalloc_noio_restore(flags); + ___free_pages_bulk(data.pages, nr_pages); if (ret) break; @@ -385,7 +402,7 @@ static int __kasan_populate_vmalloc(unsigned long start, unsigned long end) return ret; } -int kasan_populate_vmalloc(unsigned long addr, unsigned long size) +int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask) { unsigned long shadow_start, shadow_end; int ret; @@ -414,7 +431,7 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size) shadow_start = PAGE_ALIGN_DOWN(shadow_start); shadow_end = PAGE_ALIGN(shadow_end); - ret = __kasan_populate_vmalloc(shadow_start, shadow_end); + ret = __kasan_populate_vmalloc(shadow_start, shadow_end, gfp_mask); if (ret) return ret; diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 6dbcdceecae1..5edd536ba9d2 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2026,6 +2026,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, if (unlikely(!vmap_initialized)) return ERR_PTR(-EBUSY); + /* Only reclaim behaviour flags are relevant. */ + gfp_mask = gfp_mask & GFP_RECLAIM_MASK; might_sleep(); /* @@ -2038,8 +2040,6 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, */ va = node_alloc(size, align, vstart, vend, &addr, &vn_id); if (!va) { - gfp_mask = gfp_mask & GFP_RECLAIM_MASK; - va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node); if (unlikely(!va)) return ERR_PTR(-ENOMEM); @@ -2089,7 +2089,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, BUG_ON(va->va_start < vstart); BUG_ON(va->va_end > vend); - ret = kasan_populate_vmalloc(addr, size); + ret = kasan_populate_vmalloc(addr, size, gfp_mask); if (ret) { free_vmap_area(va); return ERR_PTR(ret); @@ -4826,7 +4826,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets, /* populate the kasan shadow space */ for (area = 0; area < nr_vms; area++) { - if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area])) + if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area], GFP_KERNEL)) goto err_free_shadow; } -- 2.47.2

3 months, 1 week

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[PATCH v4 1/1] eventpoll: Replace rwlock with spinlock

by Nam Cao

The ready event list of an epoll object is protected by read-write semaphore: - The consumer (waiter) acquires the write lock and takes items. - the producer (waker) takes the read lock and adds items. The point of this design is enabling epoll to scale well with large number of producers, as multiple producers can hold the read lock at the same time. Unfortunately, this implementation may cause scheduling priority inversion problem. Suppose the consumer has higher scheduling priority than the producer. The consumer needs to acquire the write lock, but may be blocked by the producer holding the read lock. Since read-write semaphore does not support priority-boosting for the readers (even with CONFIG_PREEMPT_RT=y), we have a case of priority inversion: a higher priority consumer is blocked by a lower priority producer. This problem was reported in [1]. Furthermore, this could also cause stall problem, as described in [2]. Fix this problem by replacing rwlock with spinlock. This reduces the event bandwidth, as the producers now have to contend with each other for the spinlock. According to the benchmark from https://github.com/rouming/test-tools/blob/master/stress-epoll.c: On 12 x86 CPUs: Before After Diff threads events/ms events/ms 8 7162 4956 -31% 16 8733 5383 -38% 32 7968 5572 -30% 64 10652 5739 -46% 128 11236 5931 -47% On 4 riscv CPUs: Before After Diff threads events/ms events/ms 8 2958 2833 -4% 16 3323 3097 -7% 32 3451 3240 -6% 64 3554 3178 -11% 128 3601 3235 -10% Although the numbers look bad, it should be noted that this benchmark creates multiple threads who do nothing except constantly generating new epoll events, thus contention on the spinlock is high. For real workload, the event rate is likely much lower, and the performance drop is not as bad. Using another benchmark (perf bench epoll wait) where spinlock contention is lower, improvement is even observed on x86: On 12 x86 CPUs: Before: Averaged 110279 operations/sec (+- 1.09%), total secs = 8 After: Averaged 114577 operations/sec (+- 2.25%), total secs = 8 On 4 riscv CPUs: Before: Averaged 175767 operations/sec (+- 0.62%), total secs = 8 After: Averaged 167396 operations/sec (+- 0.23%), total secs = 8 In conclusion, no one is likely to be upset over this change. After all, spinlock was used originally for years, and the commit which converted to rwlock didn't mention a real workload, just that the benchmark numbers are nice. This patch is not exactly the revert of commit a218cc491420 ("epoll: use rwlock in order to reduce ep_poll_callback() contention"), because git revert conflicts in some places which are not obvious on the resolution. This patch is intended to be backported, therefore go with the obvious approach: - Replace rwlock_t with spinlock_t one to one - Delete list_add_tail_lockless() and chain_epi_lockless(). These were introduced to allow producers to concurrently add items to the list. But now that spinlock no longer allows producers to touch the event list concurrently, these two functions are not necessary anymore. Fixes: a218cc491420 ("epoll: use rwlock in order to reduce ep_poll_callback() contention") Signed-off-by: Nam Cao <namcao(a)linutronix.de> Cc: stable(a)vger.kernel.org --- fs/eventpoll.c | 139 +++++++++---------------------------------------- 1 file changed, 26 insertions(+), 113 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 0fbf5dfedb24..a171f7e7dacc 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -46,10 +46,10 @@ * * 1) epnested_mutex (mutex) * 2) ep->mtx (mutex) - * 3) ep->lock (rwlock) + * 3) ep->lock (spinlock) * * The acquire order is the one listed above, from 1 to 3. - * We need a rwlock (ep->lock) because we manipulate objects + * We need a spinlock (ep->lock) because we manipulate objects * from inside the poll callback, that might be triggered from * a wake_up() that in turn might be called from IRQ context. * So we can't sleep inside the poll callback and hence we need @@ -195,7 +195,7 @@ struct eventpoll { struct list_head rdllist; /* Lock which protects rdllist and ovflist */ - rwlock_t lock; + spinlock_t lock; /* RB tree root used to store monitored fd structs */ struct rb_root_cached rbr; @@ -740,10 +740,10 @@ static void ep_start_scan(struct eventpoll *ep, struct list_head *txlist) * in a lockless way. */ lockdep_assert_irqs_enabled(); - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); list_splice_init(&ep->rdllist, txlist); WRITE_ONCE(ep->ovflist, NULL); - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); } static void ep_done_scan(struct eventpoll *ep, @@ -751,7 +751,7 @@ static void ep_done_scan(struct eventpoll *ep, { struct epitem *epi, *nepi; - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); /* * During the time we spent inside the "sproc" callback, some * other events might have been queued by the poll callback. @@ -792,7 +792,7 @@ static void ep_done_scan(struct eventpoll *ep, wake_up(&ep->wq); } - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); } static void ep_get(struct eventpoll *ep) @@ -867,10 +867,10 @@ static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force) rb_erase_cached(&epi->rbn, &ep->rbr); - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); if (ep_is_linked(epi)) list_del_init(&epi->rdllink); - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); wakeup_source_unregister(ep_wakeup_source(epi)); /* @@ -1151,7 +1151,7 @@ static int ep_alloc(struct eventpoll **pep) return -ENOMEM; mutex_init(&ep->mtx); - rwlock_init(&ep->lock); + spin_lock_init(&ep->lock); init_waitqueue_head(&ep->wq); init_waitqueue_head(&ep->poll_wait); INIT_LIST_HEAD(&ep->rdllist); @@ -1238,100 +1238,10 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, } #endif /* CONFIG_KCMP */ -/* - * Adds a new entry to the tail of the list in a lockless way, i.e. - * multiple CPUs are allowed to call this function concurrently. - * - * Beware: it is necessary to prevent any other modifications of the - * existing list until all changes are completed, in other words - * concurrent list_add_tail_lockless() calls should be protected - * with a read lock, where write lock acts as a barrier which - * makes sure all list_add_tail_lockless() calls are fully - * completed. - * - * Also an element can be locklessly added to the list only in one - * direction i.e. either to the tail or to the head, otherwise - * concurrent access will corrupt the list. - * - * Return: %false if element has been already added to the list, %true - * otherwise. - */ -static inline bool list_add_tail_lockless(struct list_head *new, - struct list_head *head) -{ - struct list_head *prev; - - /* - * This is simple 'new->next = head' operation, but cmpxchg() - * is used in order to detect that same element has been just - * added to the list from another CPU: the winner observes - * new->next == new. - */ - if (!try_cmpxchg(&new->next, &new, head)) - return false; - - /* - * Initially ->next of a new element must be updated with the head - * (we are inserting to the tail) and only then pointers are atomically - * exchanged. XCHG guarantees memory ordering, thus ->next should be - * updated before pointers are actually swapped and pointers are - * swapped before prev->next is updated. - */ - - prev = xchg(&head->prev, new); - - /* - * It is safe to modify prev->next and new->prev, because a new element - * is added only to the tail and new->next is updated before XCHG. - */ - - prev->next = new; - new->prev = prev; - - return true; -} - -/* - * Chains a new epi entry to the tail of the ep->ovflist in a lockless way, - * i.e. multiple CPUs are allowed to call this function concurrently. - * - * Return: %false if epi element has been already chained, %true otherwise. - */ -static inline bool chain_epi_lockless(struct epitem *epi) -{ - struct eventpoll *ep = epi->ep; - - /* Fast preliminary check */ - if (epi->next != EP_UNACTIVE_PTR) - return false; - - /* Check that the same epi has not been just chained from another CPU */ - if (cmpxchg(&epi->next, EP_UNACTIVE_PTR, NULL) != EP_UNACTIVE_PTR) - return false; - - /* Atomically exchange tail */ - epi->next = xchg(&ep->ovflist, epi); - - return true; -} - /* * This is the callback that is passed to the wait queue wakeup * mechanism. It is called by the stored file descriptors when they * have events to report. - * - * This callback takes a read lock in order not to contend with concurrent - * events from another file descriptor, thus all modifications to ->rdllist - * or ->ovflist are lockless. Read lock is paired with the write lock from - * ep_start/done_scan(), which stops all list modifications and guarantees - * that lists state is seen correctly. - * - * Another thing worth to mention is that ep_poll_callback() can be called - * concurrently for the same @epi from different CPUs if poll table was inited - * with several wait queues entries. Plural wakeup from different CPUs of a - * single wait queue is serialized by wq.lock, but the case when multiple wait - * queues are used should be detected accordingly. This is detected using - * cmpxchg() operation. */ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) { @@ -1342,7 +1252,7 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v unsigned long flags; int ewake = 0; - read_lock_irqsave(&ep->lock, flags); + spin_lock_irqsave(&ep->lock, flags); ep_set_busy_poll_napi_id(epi); @@ -1371,12 +1281,15 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v * chained in ep->ovflist and requeued later on. */ if (READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR) { - if (chain_epi_lockless(epi)) + if (epi->next == EP_UNACTIVE_PTR) { + epi->next = READ_ONCE(ep->ovflist); + WRITE_ONCE(ep->ovflist, epi); ep_pm_stay_awake_rcu(epi); + } } else if (!ep_is_linked(epi)) { /* In the usual case, add event to ready list. */ - if (list_add_tail_lockless(&epi->rdllink, &ep->rdllist)) - ep_pm_stay_awake_rcu(epi); + list_add_tail(&epi->rdllink, &ep->rdllist); + ep_pm_stay_awake_rcu(epi); } /* @@ -1409,7 +1322,7 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v pwake++; out_unlock: - read_unlock_irqrestore(&ep->lock, flags); + spin_unlock_irqrestore(&ep->lock, flags); /* We have to call this outside the lock */ if (pwake) @@ -1744,7 +1657,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, } /* We have to drop the new item inside our item list to keep track of it */ - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); /* record NAPI ID of new item if present */ ep_set_busy_poll_napi_id(epi); @@ -1761,7 +1674,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, pwake++; } - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); /* We have to call this outside the lock */ if (pwake) @@ -1825,7 +1738,7 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, * list, push it inside. */ if (ep_item_poll(epi, &pt, 1)) { - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); if (!ep_is_linked(epi)) { list_add_tail(&epi->rdllink, &ep->rdllist); ep_pm_stay_awake(epi); @@ -1836,7 +1749,7 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, if (waitqueue_active(&ep->poll_wait)) pwake++; } - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); } /* We have to call this outside the lock */ @@ -2088,7 +2001,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, init_wait(&wait); wait.func = ep_autoremove_wake_function; - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); /* * Barrierless variant, waitqueue_active() is called under * the same lock on wakeup ep_poll_callback() side, so it @@ -2107,7 +2020,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, if (!eavail) __add_wait_queue_exclusive(&ep->wq, &wait); - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); if (!eavail) timed_out = !ep_schedule_timeout(to) || @@ -2123,7 +2036,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, eavail = 1; if (!list_empty_careful(&wait.entry)) { - write_lock_irq(&ep->lock); + spin_lock_irq(&ep->lock); /* * If the thread timed out and is not on the wait queue, * it means that the thread was woken up after its @@ -2134,7 +2047,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, if (timed_out) eavail = list_empty(&wait.entry); __remove_wait_queue(&ep->wq, &wait); - write_unlock_irq(&ep->lock); + spin_unlock_irq(&ep->lock); } } } -- 2.39.5

3 months, 1 week

5
7
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[PATCH v2 1/7] efi: Add missing static initializer for efi_mm::cpus_allowed_lock

by Ard Biesheuvel

From: Ard Biesheuvel <ardb(a)kernel.org> Initialize the cpus_allowed_lock struct member of efi_mm. Cc: <stable(a)vger.kernel.org> Signed-off-by: Ard Biesheuvel <ardb(a)kernel.org> --- drivers/firmware/efi/efi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 1ce428e2ac8a..fc407d891348 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -74,6 +74,9 @@ struct mm_struct efi_mm = { .page_table_lock = __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock), .mmlist = LIST_HEAD_INIT(efi_mm.mmlist), .cpu_bitmap = { [BITS_TO_LONGS(NR_CPUS)] = 0}, +#ifdef CONFIG_SCHED_MM_CID + .cpus_allowed_lock = __RAW_SPIN_LOCK_UNLOCKED(efi_mm.cpus_allowed_lock), +#endif }; struct workqueue_struct *efi_rts_wq; -- 2.51.0.355.g5224444f11-goog

3 months, 1 week

1
0
0 0

[PATCH v3] media: vidtv: initialize local pointers upon transfer of memory ownership

by Jeongjun Park

vidtv_channel_si_init() creates a temporary list (program, service, event) and ownership of the memory itself is transferred to the PAT/SDT/EIT tables through vidtv_psi_pat_program_assign(), vidtv_psi_sdt_service_assign(), vidtv_psi_eit_event_assign(). The problem here is that the local pointer where the memory ownership transfer was completed is not initialized to NULL. This causes the vidtv_psi_pmt_create_sec_for_each_pat_entry() function to fail, and in the flow that jumps to free_eit, the memory that was freed by vidtv_psi_*_table_destroy() can be accessed again by vidtv_psi_*_event_destroy() due to the uninitialized local pointer, so it is freed once again. Therefore, to prevent use-after-free and double-free vulnerability, local pointers must be initialized to NULL when transferring memory ownership. Cc: <stable(a)vger.kernel.org> Reported-by: syzbot+1d9c0edea5907af239e0(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1d9c0edea5907af239e0 Fixes: 3be8037960bc ("media: vidtv: add error checks") Signed-off-by: Jeongjun Park <aha310510(a)gmail.com> --- v3: Improved patch description wording - Link to v2: https://lore.kernel.org/all/20250904054000.3848107-1-aha310510@gmail.com/ v2: Improved patch description wording and CC stable mailing list - Link to v1: https://lore.kernel.org/all/20250822065849.1145572-1-aha310510@gmail.com/ --- drivers/media/test-drivers/vidtv/vidtv_channel.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/media/test-drivers/vidtv/vidtv_channel.c b/drivers/media/test-drivers/vidtv/vidtv_channel.c index f3023e91b3eb..3541155c6fc6 100644 --- a/drivers/media/test-drivers/vidtv/vidtv_channel.c +++ b/drivers/media/test-drivers/vidtv/vidtv_channel.c @@ -461,12 +461,15 @@ int vidtv_channel_si_init(struct vidtv_mux *m) /* assemble all programs and assign to PAT */ vidtv_psi_pat_program_assign(m->si.pat, programs); + programs = NULL; /* assemble all services and assign to SDT */ vidtv_psi_sdt_service_assign(m->si.sdt, services); + services = NULL; /* assemble all events and assign to EIT */ vidtv_psi_eit_event_assign(m->si.eit, events); + events = NULL; m->si.pmt_secs = vidtv_psi_pmt_create_sec_for_each_pat_entry(m->si.pat, m->pcr_pid); --

3 months, 1 week

2
1
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[PATCH] iommu/s390: Fix memory corruption when using identity domain

by Matthew Rosato

zpci_get_iommu_ctrs() returns counter information to be reported as part of device statistics; these counters are stored as part of the s390_domain. The problem, however, is that the identity domain is not backed by an s390_domain and so the conversion via to_s390_domain() yields a bad address that is zero'd initially and read on-demand later via a sysfs read. These counters aren't necessary for the identity domain; just return NULL in this case. This issue was discovered via KASAN with reports that look like: BUG: KASAN: global-out-of-bounds in zpci_fmb_enable_device when using the identity domain for a device on s390. Cc: stable(a)vger.kernel.org Fixes: 64af12c6ec3a ("iommu/s390: implement iommu passthrough via identity domain") Reported-by: Cam Miller <cam(a)linux.ibm.com> Signed-off-by: Matthew Rosato <mjrosato(a)linux.ibm.com> --- drivers/iommu/s390-iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c index 9c80d61deb2c..d7370347c910 100644 --- a/drivers/iommu/s390-iommu.c +++ b/drivers/iommu/s390-iommu.c @@ -1032,7 +1032,8 @@ struct zpci_iommu_ctrs *zpci_get_iommu_ctrs(struct zpci_dev *zdev) lockdep_assert_held(&zdev->dom_lock); - if (zdev->s390_domain->type == IOMMU_DOMAIN_BLOCKED) + if (zdev->s390_domain->type == IOMMU_DOMAIN_BLOCKED || + zdev->s390_domain->type == IOMMU_DOMAIN_IDENTITY) return NULL; s390_domain = to_s390_domain(zdev->s390_domain); -- 2.50.1

3 months, 1 week

5
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Re: [PATCH] iommu/amd: Fix ivrs_base memleak in early_amd_iommu_init()

by Joerg Roedel

On Fri, Aug 22, 2025 at 10:49:15AM +0800, Zhen Ni wrote: > Fix a permanent ACPI table memory leak in early_amd_iommu_init() when > CMPXCHG16B feature is not supported > > Fixes: 82582f85ed22 ("iommu/amd: Disable AMD IOMMU if CMPXCHG16B feature is not supported") > Cc: stable(a)vger.kernel.org > Signed-off-by: Zhen Ni <zhen.ni(a)easystack.cn> > --- > drivers/iommu/amd/init.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) Applied for -rc, thanks.

3 months, 1 week

1
0
0 0

[PATCH] mm/memcg: v1: account event registrations and drop world-writable cgroup.event_control

by Stanislav Fort

In cgroup v1, the legacy cgroup.event_control file is world-writable and allows unprivileged users to register unbounded events and thresholds. Each registration allocates kernel memory without capping or memcg charging, which can be abused to exhaust kernel memory in affected configurations. Make the following minimal changes: - Account allocations with __GFP_ACCOUNT in event and threshold registration. - Remove CFTYPE_WORLD_WRITABLE from cgroup.event_control to make it owner-writable. This does not affect cgroup v2. Allocations are still subject to kmem accounting being enabled, but this reduces unbounded global growth. Reported-by: Stanislav Fort <disclosure(a)aisle.com> Acked-by: Johannes Weiner <hannes(a)cmpxchg.org> Cc: stable(a)vger.kernel.org Signed-off-by: Stanislav Fort <disclosure(a)aisle.com> --- mm/memcontrol-v1.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c index 4b94731305b9..9374785319ab 100644 --- a/mm/memcontrol-v1.c +++ b/mm/memcontrol-v1.c @@ -761,7 +761,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, size = thresholds->primary ? thresholds->primary->size + 1 : 1; /* Allocate memory for new array of thresholds */ - new = kmalloc(struct_size(new, entries, size), GFP_KERNEL); + new = kmalloc(struct_size(new, entries, size), GFP_KERNEL | __GFP_ACCOUNT); if (!new) { ret = -ENOMEM; goto unlock; @@ -924,7 +924,7 @@ static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg, { struct mem_cgroup_eventfd_list *event; - event = kmalloc(sizeof(*event), GFP_KERNEL); + event = kmalloc(sizeof(*event), GFP_KERNEL | __GFP_ACCOUNT); if (!event) return -ENOMEM; @@ -1087,7 +1087,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of, CLASS(fd, cfile)(cfd); - event = kzalloc(sizeof(*event), GFP_KERNEL); + event = kzalloc(sizeof(*event), GFP_KERNEL | __GFP_ACCOUNT); if (!event) return -ENOMEM; @@ -2053,7 +2053,7 @@ struct cftype mem_cgroup_legacy_files[] = { { .name = "cgroup.event_control", /* XXX: for compat */ .write = memcg_write_event_control, - .flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE, + .flags = CFTYPE_NO_PREFIX, }, { .name = "swappiness", -- 2.39.3 (Apple Git-146)

3 months, 1 week

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