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[PATCH v2] mm/ksm: fix flag-dropping behavior in ksm_madvise

by Jakub Acs

syzkaller discovered the following crash: (kernel BUG) [ 44.607039] ------------[ cut here ]------------ [ 44.607422] kernel BUG at mm/userfaultfd.c:2067! [ 44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none) [ 44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460 <snip other registers, drop unreliable trace> [ 44.617726] Call Trace: [ 44.617926] <TASK> [ 44.619284] userfaultfd_release+0xef/0x1b0 [ 44.620976] __fput+0x3f9/0xb60 [ 44.621240] fput_close_sync+0x110/0x210 [ 44.622222] __x64_sys_close+0x8f/0x120 [ 44.622530] do_syscall_64+0x5b/0x2f0 [ 44.622840] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 44.623244] RIP: 0033:0x7f365bb3f227 Kernel panics because it detects UFFD inconsistency during userfaultfd_release_all(). Specifically, a VMA which has a valid pointer to vma->vm_userfaultfd_ctx, but no UFFD flags in vma->vm_flags. The inconsistency is caused in ksm_madvise(): when user calls madvise() with MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode, it accidentally clears all flags stored in the upper 32 bits of vma->vm_flags. Assuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and int are 32-bit wide. This setup causes the following mishap during the &= ~VM_MERGEABLE assignment. VM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000'0000. After ~ is applied, it becomes 0x7fff'ffff unsigned int, which is then promoted to unsigned long before the & operation. This promotion fills upper 32 bits with leading 0s, as we're doing unsigned conversion (and even for a signed conversion, this wouldn't help as the leading bit is 0). & operation thus ends up AND-ing vm_flags with 0x0000'0000'7fff'ffff instead of intended 0xffff'ffff'7fff'ffff and hence accidentally clears the upper 32-bits of its value. Fix it by changing `VM_MERGEABLE` constant to unsigned long. Modify all other VM_* flags constants for consistency. Note: other VM_* flags are not affected: This only happens to the VM_MERGEABLE flag, as the other VM_* flags are all constants of type int and after ~ operation, they end up with leading 1 and are thus converted to unsigned long with leading 1s. Note 2: After commit 31defc3b01d9 ("userfaultfd: remove (VM_)BUG_ON()s"), this is no longer a kernel BUG, but a WARNING at the same place: [ 45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067 but the root-cause (flag-drop) remains the same. Fixes: 7677f7fd8be76 ("userfaultfd: add minor fault registration mode") Signed-off-by: Jakub Acs <acsjakub(a)amazon.de> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Xu Xin <xu.xin16(a)zte.com.cn> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: Peter Xu <peterx(a)redhat.com> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: linux-mm(a)kvack.org Cc: linux-kernel(a)vger.kernel.org Cc: stable(a)vger.kernel.org --- v1 -> v2: - fix by adding ul to flag constants instead of explicit cast. - drop Mike Kravetz <mike.kravetz(a)oracle.com> from cc, as the mail returned v1: https://lore.kernel.org/all/20250930063921.62354-1-acsjakub@amazon.de/ include/linux/mm.h | 72 +++++++++++++++++++++++----------------------- 1 file changed, 36 insertions(+), 36 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 1ae97a0b8ec7..26a5c0f78b36 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -246,57 +246,57 @@ extern unsigned int kobjsize(const void *objp); * vm_flags in vm_area_struct, see mm_types.h. * When changing, update also include/trace/events/mmflags.h */ -#define VM_NONE 0x00000000 +#define VM_NONE 0x00000000ul -#define VM_READ 0x00000001 /* currently active flags */ -#define VM_WRITE 0x00000002 -#define VM_EXEC 0x00000004 -#define VM_SHARED 0x00000008 +#define VM_READ 0x00000001ul /* currently active flags */ +#define VM_WRITE 0x00000002ul +#define VM_EXEC 0x00000004ul +#define VM_SHARED 0x00000008ul /* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */ -#define VM_MAYREAD 0x00000010 /* limits for mprotect() etc */ -#define VM_MAYWRITE 0x00000020 -#define VM_MAYEXEC 0x00000040 -#define VM_MAYSHARE 0x00000080 +#define VM_MAYREAD 0x00000010ul /* limits for mprotect() etc */ +#define VM_MAYWRITE 0x00000020ul +#define VM_MAYEXEC 0x00000040ul +#define VM_MAYSHARE 0x00000080ul -#define VM_GROWSDOWN 0x00000100 /* general info on the segment */ +#define VM_GROWSDOWN 0x00000100ul /* general info on the segment */ #ifdef CONFIG_MMU -#define VM_UFFD_MISSING 0x00000200 /* missing pages tracking */ +#define VM_UFFD_MISSING 0x00000200ul /* missing pages tracking */ #else /* CONFIG_MMU */ -#define VM_MAYOVERLAY 0x00000200 /* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */ -#define VM_UFFD_MISSING 0 +#define VM_MAYOVERLAY 0x00000200ul /* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */ +#define VM_UFFD_MISSING 0ul #endif /* CONFIG_MMU */ -#define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */ -#define VM_UFFD_WP 0x00001000 /* wrprotect pages tracking */ +#define VM_PFNMAP 0x00000400ul /* Page-ranges managed without "struct page", just pure PFN */ +#define VM_UFFD_WP 0x00001000ul /* wrprotect pages tracking */ -#define VM_LOCKED 0x00002000 -#define VM_IO 0x00004000 /* Memory mapped I/O or similar */ +#define VM_LOCKED 0x00002000ul +#define VM_IO 0x00004000ul /* Memory mapped I/O or similar */ /* Used by sys_madvise() */ -#define VM_SEQ_READ 0x00008000 /* App will access data sequentially */ -#define VM_RAND_READ 0x00010000 /* App will not benefit from clustered reads */ - -#define VM_DONTCOPY 0x00020000 /* Do not copy this vma on fork */ -#define VM_DONTEXPAND 0x00040000 /* Cannot expand with mremap() */ -#define VM_LOCKONFAULT 0x00080000 /* Lock the pages covered when they are faulted in */ -#define VM_ACCOUNT 0x00100000 /* Is a VM accounted object */ -#define VM_NORESERVE 0x00200000 /* should the VM suppress accounting */ -#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */ -#define VM_SYNC 0x00800000 /* Synchronous page faults */ -#define VM_ARCH_1 0x01000000 /* Architecture-specific flag */ -#define VM_WIPEONFORK 0x02000000 /* Wipe VMA contents in child. */ -#define VM_DONTDUMP 0x04000000 /* Do not include in the core dump */ +#define VM_SEQ_READ 0x00008000ul /* App will access data sequentially */ +#define VM_RAND_READ 0x00010000ul /* App will not benefit from clustered reads */ + +#define VM_DONTCOPY 0x00020000ul /* Do not copy this vma on fork */ +#define VM_DONTEXPAND 0x00040000ul /* Cannot expand with mremap() */ +#define VM_LOCKONFAULT 0x00080000ul /* Lock the pages covered when they are faulted in */ +#define VM_ACCOUNT 0x00100000ul /* Is a VM accounted object */ +#define VM_NORESERVE 0x00200000ul /* should the VM suppress accounting */ +#define VM_HUGETLB 0x00400000ul /* Huge TLB Page VM */ +#define VM_SYNC 0x00800000ul /* Synchronous page faults */ +#define VM_ARCH_1 0x01000000ul /* Architecture-specific flag */ +#define VM_WIPEONFORK 0x02000000ul /* Wipe VMA contents in child. */ +#define VM_DONTDUMP 0x04000000ul /* Do not include in the core dump */ #ifdef CONFIG_MEM_SOFT_DIRTY -# define VM_SOFTDIRTY 0x08000000 /* Not soft dirty clean area */ +# define VM_SOFTDIRTY 0x08000000ul /* Not soft dirty clean area */ #else -# define VM_SOFTDIRTY 0 +# define VM_SOFTDIRTY 0ul #endif -#define VM_MIXEDMAP 0x10000000 /* Can contain "struct page" and pure PFN pages */ -#define VM_HUGEPAGE 0x20000000 /* MADV_HUGEPAGE marked this vma */ -#define VM_NOHUGEPAGE 0x40000000 /* MADV_NOHUGEPAGE marked this vma */ -#define VM_MERGEABLE 0x80000000 /* KSM may merge identical pages */ +#define VM_MIXEDMAP 0x10000000ul /* Can contain "struct page" and pure PFN pages */ +#define VM_HUGEPAGE 0x20000000ul /* MADV_HUGEPAGE marked this vma */ +#define VM_NOHUGEPAGE 0x40000000ul /* MADV_NOHUGEPAGE marked this vma */ +#define VM_MERGEABLE 0x80000000ul /* KSM may merge identical pages */ #ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS #define VM_HIGH_ARCH_BIT_0 32 /* bit only usable on 64-bit architectures */ -- 2.47.3 Amazon Web Services Development Center Germany GmbH Tamara-Danz-Str. 13 10243 Berlin Geschaeftsfuehrung: Christian Schlaeger Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597

3 months, 1 week

Re: [PATCH] dma-mapping: fix direction in dma_alloc direction traces

by Petr Tesarik

Cc: stable(a)vger.kernel.org (One day, I'll finally remember, I promise.) Petr T On Wed, 1 Oct 2025 08:10:28 +0200 Petr Tesarik <ptesarik(a)suse.com> wrote: > Set __entry->dir to the actual "dir" parameter of all trace events > in dma_alloc_class. This struct member was left uninitialized by > mistake. > > Signed-off-by: Petr Tesarik <ptesarik(a)suse.com> > Fixes: 3afff779a725 ("dma-mapping: trace dma_alloc/free direction") > --- > include/trace/events/dma.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/trace/events/dma.h b/include/trace/events/dma.h > index d8ddc27b6a7c8..945fcbaae77e9 100644 > --- a/include/trace/events/dma.h > +++ b/include/trace/events/dma.h > @@ -134,6 +134,7 @@ DECLARE_EVENT_CLASS(dma_alloc_class, > __entry->dma_addr = dma_addr; > __entry->size = size; > __entry->flags = flags; > + __entry->dir = dir; > __entry->attrs = attrs; > ), >

3 months, 1 week

[PATCH v3] fbdev/simplefb: Fix use after free in simplefb_detach_genpds()

by Janne Grunau

The pm_domain cleanup can not be devres managed as it uses struct simplefb_par which is allocated within struct fb_info by framebuffer_alloc(). This allocation is explicitly freed by unregister_framebuffer() in simplefb_remove(). Devres managed cleanup runs after the device remove call and thus can no longer access struct simplefb_par. Call simplefb_detach_genpds() explicitly from simplefb_destroy() like the cleanup functions for clocks and regulators. Fixes an use after free on M2 Mac mini during aperture_remove_conflicting_devices() using the downstream asahi kernel with Debian's kernel config. For unknown reasons this started to consistently dereference an invalid pointer in v6.16.3 based kernels. [ 6.736134] BUG: KASAN: slab-use-after-free in simplefb_detach_genpds+0x58/0x220 [ 6.743545] Read of size 4 at addr ffff8000304743f0 by task (udev-worker)/227 [ 6.750697] [ 6.752182] CPU: 6 UID: 0 PID: 227 Comm: (udev-worker) Tainted: G S 6.16.3-asahi+ #16 PREEMPTLAZY [ 6.752186] Tainted: [S]=CPU_OUT_OF_SPEC [ 6.752187] Hardware name: Apple Mac mini (M2, 2023) (DT) [ 6.752189] Call trace: [ 6.752190] show_stack+0x34/0x98 (C) [ 6.752194] dump_stack_lvl+0x60/0x80 [ 6.752197] print_report+0x17c/0x4d8 [ 6.752201] kasan_report+0xb4/0x100 [ 6.752206] __asan_report_load4_noabort+0x20/0x30 [ 6.752209] simplefb_detach_genpds+0x58/0x220 [ 6.752213] devm_action_release+0x50/0x98 [ 6.752216] release_nodes+0xd0/0x2c8 [ 6.752219] devres_release_all+0xfc/0x178 [ 6.752221] device_unbind_cleanup+0x28/0x168 [ 6.752224] device_release_driver_internal+0x34c/0x470 [ 6.752228] device_release_driver+0x20/0x38 [ 6.752231] bus_remove_device+0x1b0/0x380 [ 6.752234] device_del+0x314/0x820 [ 6.752238] platform_device_del+0x3c/0x1e8 [ 6.752242] platform_device_unregister+0x20/0x50 [ 6.752246] aperture_detach_platform_device+0x1c/0x30 [ 6.752250] aperture_detach_devices+0x16c/0x290 [ 6.752253] aperture_remove_conflicting_devices+0x34/0x50 ... [ 6.752343] [ 6.967409] Allocated by task 62: [ 6.970724] kasan_save_stack+0x3c/0x70 [ 6.974560] kasan_save_track+0x20/0x40 [ 6.978397] kasan_save_alloc_info+0x40/0x58 [ 6.982670] __kasan_kmalloc+0xd4/0xd8 [ 6.986420] __kmalloc_noprof+0x194/0x540 [ 6.990432] framebuffer_alloc+0xc8/0x130 [ 6.994444] simplefb_probe+0x258/0x2378 ... [ 7.054356] [ 7.055838] Freed by task 227: [ 7.058891] kasan_save_stack+0x3c/0x70 [ 7.062727] kasan_save_track+0x20/0x40 [ 7.066565] kasan_save_free_info+0x4c/0x80 [ 7.070751] __kasan_slab_free+0x6c/0xa0 [ 7.074675] kfree+0x10c/0x380 [ 7.077727] framebuffer_release+0x5c/0x90 [ 7.081826] simplefb_destroy+0x1b4/0x2c0 [ 7.085837] put_fb_info+0x98/0x100 [ 7.089326] unregister_framebuffer+0x178/0x320 [ 7.093861] simplefb_remove+0x3c/0x60 [ 7.097611] platform_remove+0x60/0x98 [ 7.101361] device_remove+0xb8/0x160 [ 7.105024] device_release_driver_internal+0x2fc/0x470 [ 7.110256] device_release_driver+0x20/0x38 [ 7.114529] bus_remove_device+0x1b0/0x380 [ 7.118628] device_del+0x314/0x820 [ 7.122116] platform_device_del+0x3c/0x1e8 [ 7.126302] platform_device_unregister+0x20/0x50 [ 7.131012] aperture_detach_platform_device+0x1c/0x30 [ 7.136157] aperture_detach_devices+0x16c/0x290 [ 7.140779] aperture_remove_conflicting_devices+0x34/0x50 ... Reported-by: Daniel Huhardeaux <tech(a)tootai.net> Cc: stable(a)vger.kernel.org Fixes: 92a511a568e44 ("fbdev/simplefb: Add support for generic power-domains") Signed-off-by: Janne Grunau <j(a)jannau.net> --- Changes in v3: - release power-domains on probe errors - set par->num_genpds when it's <= 1 - set par->num_genpds to 0 after detaching - Link to v2: https://lore.kernel.org/r/20250908-simplefb-genpd-uaf-v2-1-f88a0d9d880f@jan… Changes in v2: - reworked change due to missed use of `par->num_genpds` before setting it. Missed in testing due to mixing up FB_SIMPLE and SYSFB_SIMPLEFB. - Link to v1: https://lore.kernel.org/r/20250901-simplefb-genpd-uaf-v1-1-0d9f3a34c4dc@jan… --- drivers/video/fbdev/simplefb.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c index 1893815dc67f4c1403eea42c0e10a7ead4d96ba9..6acf5a00c2bacfab89c3a63bab3d8b1b091a20a8 100644 --- a/drivers/video/fbdev/simplefb.c +++ b/drivers/video/fbdev/simplefb.c @@ -93,6 +93,7 @@ struct simplefb_par { static void simplefb_clocks_destroy(struct simplefb_par *par); static void simplefb_regulators_destroy(struct simplefb_par *par); +static void simplefb_detach_genpds(void *res); /* * fb_ops.fb_destroy is called by the last put_fb_info() call at the end @@ -105,6 +106,7 @@ static void simplefb_destroy(struct fb_info *info) simplefb_regulators_destroy(info->par); simplefb_clocks_destroy(info->par); + simplefb_detach_genpds(info->par); if (info->screen_base) iounmap(info->screen_base); @@ -445,13 +447,14 @@ static void simplefb_detach_genpds(void *res) if (!IS_ERR_OR_NULL(par->genpds[i])) dev_pm_domain_detach(par->genpds[i], true); } + par->num_genpds = 0; } static int simplefb_attach_genpds(struct simplefb_par *par, struct platform_device *pdev) { struct device *dev = &pdev->dev; - unsigned int i; + unsigned int i, num_genpds; int err; err = of_count_phandle_with_args(dev->of_node, "power-domains", @@ -465,26 +468,35 @@ static int simplefb_attach_genpds(struct simplefb_par *par, return err; } - par->num_genpds = err; + num_genpds = err; /* * Single power-domain devices are handled by the driver core, so * nothing to do here. */ - if (par->num_genpds <= 1) + if (num_genpds <= 1) { + par->num_genpds = num_genpds; return 0; + } - par->genpds = devm_kcalloc(dev, par->num_genpds, sizeof(*par->genpds), + par->genpds = devm_kcalloc(dev, num_genpds, sizeof(*par->genpds), GFP_KERNEL); if (!par->genpds) return -ENOMEM; - par->genpd_links = devm_kcalloc(dev, par->num_genpds, + par->genpd_links = devm_kcalloc(dev, num_genpds, sizeof(*par->genpd_links), GFP_KERNEL); if (!par->genpd_links) return -ENOMEM; + /* + * Set par->num_genpds only after genpds and genpd_links are allocated + * to exit early from simplefb_detach_genpds() without full + * initialisation. + */ + par->num_genpds = num_genpds; + for (i = 0; i < par->num_genpds; i++) { par->genpds[i] = dev_pm_domain_attach_by_id(dev, i); if (IS_ERR(par->genpds[i])) { @@ -506,9 +518,10 @@ static int simplefb_attach_genpds(struct simplefb_par *par, dev_warn(dev, "failed to link power-domain %u\n", i); } - return devm_add_action_or_reset(dev, simplefb_detach_genpds, par); + return 0; } #else +static void simplefb_detach_genpds(void *res) { } static int simplefb_attach_genpds(struct simplefb_par *par, struct platform_device *pdev) { @@ -622,18 +635,20 @@ static int simplefb_probe(struct platform_device *pdev) ret = devm_aperture_acquire_for_platform_device(pdev, par->base, par->size); if (ret) { dev_err(&pdev->dev, "Unable to acquire aperture: %d\n", ret); - goto error_regulators; + goto error_genpds; } ret = register_framebuffer(info); if (ret < 0) { dev_err(&pdev->dev, "Unable to register simplefb: %d\n", ret); - goto error_regulators; + goto error_genpds; } dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node); return 0; +error_genpds: + simplefb_detach_genpds(par); error_regulators: simplefb_regulators_destroy(par); error_clocks: --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20250901-simplefb-genpd-uaf-352704761a29 Best regards, -- Janne Grunau <j(a)jannau.net>

3 months, 1 week

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by llk16 9157

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3 months, 1 week

[PATCH] ext4: fix use-after-free in extent header access

by Deepanshu Kartikey

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master syzbot reported use-after-free bugs when accessing extent headers in ext4_ext_insert_extent() and ext4_ext_correct_indexes(). These occur when the extent path structure becomes invalid during operations. The crashes show two patterns: 1. In ext4_ext_map_blocks(), the extent header can be corrupted after ext4_find_extent() returns, particularly during concurrent writes to the same file. 2. In ext4_ext_correct_indexes(), accessing path[depth] causes a use-after-free, indicating the path structure itself is corrupted. This is partially exposed by commit 665575cff098 ("filemap: move prefaulting out of hot write path") which changed timing windows in the write path, making these races more likely to occur. Fix this by adding validation checks: - In ext4_ext_map_blocks(): validate the extent header after getting the path from ext4_find_extent() - In ext4_ext_correct_indexes(): validate the path pointer before dereferencing and check extent header magic While these checks are defensive and don't address the root cause of path corruption, they prevent kernel crashes from invalid memory access. A more comprehensive fix to path lifetime management may be needed in the future. Reported-by: syzbot+9db318d6167044609878(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9db318d6167044609878 Fixes: 665575cff098 ("filemap: move prefaulting out of hot write path") Cc: stable(a)vger.kernel.org Signed-off-by: Deepanshu Kartikey <kartikey406(a)gmail.com> --- fs/ext4/extents.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index ca5499e9412b..903578d5f68d 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1708,7 +1708,9 @@ static int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode, struct ext4_extent *ex; __le32 border; int k, err = 0; - + if (!path || depth < 0 || depth > EXT4_MAX_EXTENT_DEPTH) { + return -EFSCORRUPTED; + } eh = path[depth].p_hdr; ex = path[depth].p_ext; @@ -4200,6 +4202,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, unsigned int allocated_clusters = 0; struct ext4_allocation_request ar; ext4_lblk_t cluster_offset; + struct ext4_extent_header *eh; ext_debug(inode, "blocks %u/%u requested\n", map->m_lblk, map->m_len); trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags); @@ -4212,7 +4215,12 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, } depth = ext_depth(inode); - + eh = path[depth].p_hdr; + if (!eh || le16_to_cpu(eh->eh_magic) != EXT4_EXT_MAGIC) { + EXT4_ERROR_INODE(inode, "invalid extent header after find_extent"); + err = -EFSCORRUPTED; + goto out; + } /* * consistent leaf must not be empty; * this situation is possible, though, _during_ tree modification; -- 2.43.0

3 months, 1 week

+ mm-damon-vaddr-do-not-repeat-pte_offset_map_lock-until-success.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/damon/vaddr: do not repeat pte_offset_map_lock() until success has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-damon-vaddr-do-not-repeat-pte_offset_map_lock-until-success.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: SeongJae Park <sj(a)kernel.org> Subject: mm/damon/vaddr: do not repeat pte_offset_map_lock() until success Date: Mon, 29 Sep 2025 17:44:09 -0700 DAMON's virtual address space operation set implementation (vaddr) calls pte_offset_map_lock() inside the page table walk callback function. This is for reading and writing page table accessed bits. If pte_offset_map_lock() fails, it retries by returning the page table walk callback function with ACTION_AGAIN. pte_offset_map_lock() can continuously fail if the target is a pmd migration entry, though. Hence it could cause an infinite page table walk if the migration cannot be done until the page table walk is finished. This indeed caused a soft lockup when CPU hotplugging and DAMON were running in parallel. Avoid the infinite loop by simply not retrying the page table walk. DAMON is promising only a best-effort accuracy, so missing access to such pages is no problem. Link: https://lkml.kernel.org/r/20250930004410.55228-1-sj@kernel.org Fixes: 7780d04046a2 ("mm/pagewalkers: ACTION_AGAIN if pte_offset_map_lock() fails") Signed-off-by: SeongJae Park <sj(a)kernel.org> Reported-by: Xinyu Zheng <zhengxinyu6(a)huawei.com> Closes: https://lore.kernel.org/20250918030029.2652607-1-zhengxinyu6@huawei.com Acked-by: Hugh Dickins <hughd(a)google.com> Cc: <stable(a)vger.kernel.org> [6.5+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/damon/vaddr.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/mm/damon/vaddr.c~mm-damon-vaddr-do-not-repeat-pte_offset_map_lock-until-success +++ a/mm/damon/vaddr.c @@ -328,10 +328,8 @@ static int damon_mkold_pmd_entry(pmd_t * } pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); - if (!pte) { - walk->action = ACTION_AGAIN; + if (!pte) return 0; - } if (!pte_present(ptep_get(pte))) goto out; damon_ptep_mkold(pte, walk->vma, addr); @@ -481,10 +479,8 @@ regular_page: #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); - if (!pte) { - walk->action = ACTION_AGAIN; + if (!pte) return 0; - } ptent = ptep_get(pte); if (!pte_present(ptent)) goto out; _ Patches currently in -mm which might be from sj(a)kernel.org are mm-damon-vaddr-do-not-repeat-pte_offset_map_lock-until-success.patch

3 months, 1 week

+ mm-rmap-fix-soft-dirty-and-uffd-wp-bit-loss-when-remapping-zero-filled-mthp-subpage-to-shared-zeropage.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-rmap-fix-soft-dirty-and-uffd-wp-bit-loss-when-remapping-zero-filled-mthp-subpage-to-shared-zeropage.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: Lance Yang <lance.yang(a)linux.dev> Subject: mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage Date: Tue, 30 Sep 2025 16:10:40 +0800 When splitting an mTHP and replacing a zero-filled subpage with the shared zeropage, try_to_map_unused_to_zeropage() currently drops several important PTE bits. For userspace tools like CRIU, which rely on the soft-dirty mechanism for incremental snapshots, losing the soft-dirty bit means modified pages are missed, leading to inconsistent memory state after restore. As pointed out by David, the more critical uffd-wp bit is also dropped. This breaks the userfaultfd write-protection mechanism, causing writes to be silently missed by monitoring applications, which can lead to data corruption. Preserve both the soft-dirty and uffd-wp bits from the old PTE when creating the new zeropage mapping to ensure they are correctly tracked. Link: https://lkml.kernel.org/r/20250930081040.80926-1-lance.yang@linux.dev Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") Signed-off-by: Lance Yang <lance.yang(a)linux.dev> Suggested-by: David Hildenbrand <david(a)redhat.com> Suggested-by: Dev Jain <dev.jain(a)arm.com> Acked-by: David Hildenbrand <david(a)redhat.com> Reviewed-by: Dev Jain <dev.jain(a)arm.com> Acked-by: Zi Yan <ziy(a)nvidia.com> Cc: Alistair Popple <apopple(a)nvidia.com> Cc: Baolin Wang <baolin.wang(a)linux.alibaba.com> Cc: Barry Song <baohua(a)kernel.org> Cc: Byungchul Park <byungchul(a)sk.com> Cc: Gregory Price <gourry(a)gourry.net> Cc: "Huang, Ying" <ying.huang(a)linux.alibaba.com> Cc: Jann Horn <jannh(a)google.com> Cc: Joshua Hahn <joshua.hahnjy(a)gmail.com> Cc: Liam Howlett <liam.howlett(a)oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Cc: Mariano Pache <npache(a)redhat.com> Cc: Mathew Brost <matthew.brost(a)intel.com> Cc: Peter Xu <peterx(a)redhat.com> Cc: Rakie Kim <rakie.kim(a)sk.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: Usama Arif <usamaarif642(a)gmail.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Yu Zhao <yuzhao(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/migrate.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) --- a/mm/migrate.c~mm-rmap-fix-soft-dirty-and-uffd-wp-bit-loss-when-remapping-zero-filled-mthp-subpage-to-shared-zeropage +++ a/mm/migrate.c @@ -297,8 +297,7 @@ bool isolate_folio_to_list(struct folio } static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, - struct folio *folio, - unsigned long idx) + struct folio *folio, pte_t old_pte, unsigned long idx) { struct page *page = folio_page(folio, idx); pte_t newpte; @@ -307,7 +306,7 @@ static bool try_to_map_unused_to_zeropag return false; VM_BUG_ON_PAGE(!PageAnon(page), page); VM_BUG_ON_PAGE(!PageLocked(page), page); - VM_BUG_ON_PAGE(pte_present(ptep_get(pvmw->pte)), page); + VM_BUG_ON_PAGE(pte_present(old_pte), page); if (folio_test_mlocked(folio) || (pvmw->vma->vm_flags & VM_LOCKED) || mm_forbids_zeropage(pvmw->vma->vm_mm)) @@ -323,6 +322,12 @@ static bool try_to_map_unused_to_zeropag newpte = pte_mkspecial(pfn_pte(my_zero_pfn(pvmw->address), pvmw->vma->vm_page_prot)); + + if (pte_swp_soft_dirty(old_pte)) + newpte = pte_mksoft_dirty(newpte); + if (pte_swp_uffd_wp(old_pte)) + newpte = pte_mkuffd_wp(newpte); + set_pte_at(pvmw->vma->vm_mm, pvmw->address, pvmw->pte, newpte); dec_mm_counter(pvmw->vma->vm_mm, mm_counter(folio)); @@ -365,13 +370,13 @@ static bool remove_migration_pte(struct continue; } #endif + old_pte = ptep_get(pvmw.pte); if (rmap_walk_arg->map_unused_to_zeropage && - try_to_map_unused_to_zeropage(&pvmw, folio, idx)) + try_to_map_unused_to_zeropage(&pvmw, folio, old_pte, idx)) continue; folio_get(folio); pte = mk_pte(new, READ_ONCE(vma->vm_page_prot)); - old_pte = ptep_get(pvmw.pte); entry = pte_to_swp_entry(old_pte); if (!is_migration_entry_young(entry)) _ Patches currently in -mm which might be from lance.yang(a)linux.dev are hung_task-fix-warnings-caused-by-unaligned-lock-pointers.patch mm-thp-fix-mte-tag-mismatch-when-replacing-zero-filled-subpages.patch mm-rmap-fix-soft-dirty-and-uffd-wp-bit-loss-when-remapping-zero-filled-mthp-subpage-to-shared-zeropage.patch mm-clean-up-is_guard_pte_marker.patch

3 months, 1 week

[PATCH] ext4: fix use-after-free in extent header access

by Deepanshu Kartikey

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master syzbot reported multiple use-after-free bugs when accessing extent headers in various ext4 functions. These occur because extent headers can be freed by concurrent operations while other threads still hold pointers to them. The issue is triggered by racing threads performing concurrent writes to the same file. After commit 665575cff098 ("filemap: move prefaulting out of hot write path"), the write path no longer prefaults pages in the hot path, creating a wider race window where: 1. Thread A calls ext4_find_extent() and gets a path with extent headers 2. Thread A's write attempt fails, entering the slow path 3. During the gap, Thread B modifies the extent tree, freeing nodes 4. Thread A continues using the now-freed extent headers, causing UAF Fix this by validating the extent header in ext4_find_extent() before returning the path. This ensures all callers receive a valid extent path, fixing the race at a single point rather than adding checks throughout the codebase. This addresses crashes in ext4_ext_insert_extent(), ext4_ext_binsearch(), and potentially other locations that use extent paths. Reported-by: syzbot+9db318d6167044609878(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9db318d6167044609878 Fixes: 665575cff098 ("filemap: move prefaulting out of hot write path") Cc: stable(a)vger.kernel.org Signed-off-by: Deepanshu Kartikey <kartikey406(a)gmail.com> --- fs/ext4/extents.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index ca5499e9412b..04ceae5b0a34 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4200,6 +4200,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, unsigned int allocated_clusters = 0; struct ext4_allocation_request ar; ext4_lblk_t cluster_offset; + struct ext4_extent_header *eh; ext_debug(inode, "blocks %u/%u requested\n", map->m_lblk, map->m_len); trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags); @@ -4212,7 +4213,12 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, } depth = ext_depth(inode); - + eh = path[depth].p_hdr; + if (!eh || le16_to_cpu(eh->eh_magic) != EXT4_EXT_MAGIC) { + EXT4_ERROR_INODE(inode, "invalid extent header after find_extent"); + err = -EFSCORRUPTED; + goto out; + } /* * consistent leaf must not be empty; * this situation is possible, though, _during_ tree modification; -- 2.43.0

3 months, 1 week

RE: Executive Assistants and HNWI Directory to Enhance Your Marketing and Networking

by Brenda Wilson

Hi , Hope you're doing well. I wanted to check if my previous email reached you. Do you need any additional information regarding my previous email? If so, I can provide it for your review. Regards Brenda Marketing Manager Prospect Tech Connect., Please reply with REMOVE if you don't wish to receive further emails -----Original Message----- From: Brenda Wilson Subject: Executive Assistants and HNWI Directory to Enhance Your Marketing and Networking Hi , Our verified database enables accurate outreach to Executive Assistants and high-net-worth individuals. Executive Assistants (by region): USA : 50,000 contacts Europe : 15,000 contacts Canada : 2,000 contacts Middle East : 2,500 contacts HNWI & Senior Decision-Makers (by region, incl. EAs): USA : 500,000 contacts Europe : 50,000 contacts Canada : 10,000 contacts UAE : 7,500 contacts Titles we cover: Business Owners, Founders, Entrepreneurs, C-Level Executives, VPs, and Executive Assistants. Data fields: Name, Job Title, Company, URL, Email, Revenue and more. This list helps reach gatekeepers and decision-makers who oversee charter service partnerships. Happy to share prices if that helps. Eager to receive your feedback. Regards Brenda Marketing Manager Prospect Tech Connect., Please reply with REMOVE if you don't wish to receive further emails

3 months, 1 week

regression from 6.12.48 to 6.12.49: usb wlan adaptor stops working: bisected

by Wolfgang Walter

Hello,o after upgrading to 6.12.49 my wlan adapter stops working. It is detected: kernel: mt76x2u 4-2:1.0: ASIC revision: 76120044 kernel: mt76x2u 4-2:1.0: ROM patch build: 20141115060606a kernel: usb 3-4: reset high-speed USB device number 2 using xhci_hcd kernel: mt76x2u 4-2:1.0: Firmware Version: 0.0.00 kernel: mt76x2u 4-2:1.0: Build: 1 kernel: mt76x2u 4-2:1.0: Build Time: 201507311614____ but does nor work. The following 2 messages probably are relevant: kernel: mt76x2u 4-2:1.0: MAC RX failed to stop kernel: mt76x2u 4-2:1.0: MAC RX failed to stop later I see a lot of kernel: mt76x2u 4-2:1.0: error: mt76x02u_mcu_wait_resp failed with -110 I bisected it down to commit 9b28ef1e4cc07cdb35da257aa4358d0127168b68 usb: xhci: remove option to change a default ring's TRB cycle bit 9b28ef1e4cc07cdb35da257aa4358d0127168b68 is the first bad commit commit 9b28ef1e4cc07cdb35da257aa4358d0127168b68 Author: Niklas Neronin <niklas.neronin(a)linux.intel.com> Date: Wed Sep 17 08:39:07 2025 -0400 usb: xhci: remove option to change a default ring's TRB cycle bit [ Upstream commit e1b0fa863907a61e86acc19ce2d0633941907c8e ] The TRB cycle bit indicates TRB ownership by the Host Controller (HC) or Host Controller Driver (HCD). New rings are initialized with 'cycle_state' equal to one, and all its TRBs' cycle bits are set to zero. When handling ring expansion, set the source ring cycle bits to the same value as the destination ring. Move the cycle bit setting from xhci_segment_alloc() to xhci_link_rings(), and remove the 'cycle_state' argument from xhci_initialize_ring_info(). The xhci_segment_alloc() function uses kzalloc_node() to allocate segments, ensuring that all TRB cycle bits are initialized to zero. Signed-off-by: Niklas Neronin <niklas.neronin(a)linux.intel.com> Signed-off-by: Mathias Nyman <mathias.nyman(a)linux.intel.com> Link: https://lore.kernel.org/r/20241106101459.775897-12-mathias.nyman@linux.inte… Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Stable-dep-of: a5c98e8b1398 ("xhci: dbc: Fix full DbC transfer ring after several reconnects") Signed-off-by: Sasha Levin <sashal(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Regards, -- Wolfgang Walter Studierendenwerk München Oberbayern Anstalt des öffentlichen Rechts

3 months, 1 week

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