Linux-stable-mirror October 2025

linux-stable-mirror@lists.linaro.org

51 participants
37 discussions

[PATCH] ovl: check before dereferencing s_root field

by Jakub Acs

Calling intotify_show_fdinfo() on fd watching an overlayfs inode, while the overlayfs is being unmounted, can lead to dereferencing NULL ptr. This issue was found by syzkaller. Race Condition Diagram: Thread 1 Thread 2 -------- -------- generic_shutdown_super() shrink_dcache_for_umount sb->s_root = NULL | | vfs_read() | inotify_fdinfo() | * inode get from mark * | show_mark_fhandle(m, inode) | exportfs_encode_fid(inode, ..) | ovl_encode_fh(inode, ..) | ovl_check_encode_origin(inode) | * deref i_sb->s_root * | | v fsnotify_sb_delete(sb) Which then leads to: [ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] [ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none) <snip registers, unreliable trace> [ 32.143353] Call Trace: [ 32.143732] ovl_encode_fh+0xd5/0x170 [ 32.144031] exportfs_encode_inode_fh+0x12f/0x300 [ 32.144425] show_mark_fhandle+0xbe/0x1f0 [ 32.145805] inotify_fdinfo+0x226/0x2d0 [ 32.146442] inotify_show_fdinfo+0x1c5/0x350 [ 32.147168] seq_show+0x530/0x6f0 [ 32.147449] seq_read_iter+0x503/0x12a0 [ 32.148419] seq_read+0x31f/0x410 [ 32.150714] vfs_read+0x1f0/0x9e0 [ 32.152297] ksys_read+0x125/0x240 IOW ovl_check_encode_origin derefs inode->i_sb->s_root, after it was set to NULL in the unmount path. Minimize the window of opportunity by adding explicit check. Fixes: c45beebfde34 ("ovl: support encoding fid from inode with no alias") Signed-off-by: Jakub Acs <acsjakub(a)amazon.de> Cc: Miklos Szeredi <miklos(a)szeredi.hu> Cc: Amir Goldstein <amir73il(a)gmail.com> Cc: linux-unionfs(a)vger.kernel.org Cc: linux-kernel(a)vger.kernel.org Cc: stable(a)vger.kernel.org --- I'm happy to take suggestions for a better fix - I looked at taking s_umount for reading, but it wasn't clear to me for how long would the fdinfo path need to hold it. Hence the most primitive suggestion in this v1. I'm also not sure if ENOENT or EBUSY is better?.. or even something else? fs/overlayfs/export.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c index 83f80fdb1567..424c73188e06 100644 --- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -195,6 +195,8 @@ static int ovl_check_encode_origin(struct inode *inode) if (!ovl_inode_lower(inode)) return 0; + if (!inode->i_sb->s_root) + return -ENOENT; /* * Root is never indexed, so if there's an upper layer, encode upper for * root. -- 2.47.3 Amazon Web Services Development Center Germany GmbH Tamara-Danz-Str. 13 10243 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597

13 hours, 40 minutes

[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

14 hours, 46 minutes

[PATCH net v2] page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches

by Toke Høiland-Jørgensen

Helge reported that the introduction of PP_MAGIC_MASK let to crashes on boot on his 32-bit parisc machine. The cause of this is the mask is set too wide, so the page_pool_page_is_pp() incurs false positives which crashes the machine. Just disabling the check in page_pool_is_pp() will lead to the page_pool code itself malfunctioning; so instead of doing this, this patch changes the define for PP_DMA_INDEX_BITS to avoid mistaking arbitrary kernel pointers for page_pool-tagged pages. The fix relies on the kernel pointers that alias with the pp_magic field always being above PAGE_OFFSET. With this assumption, we can use the lowest bit of the value of PAGE_OFFSET as the upper bound of the PP_DMA_INDEX_MASK, which should avoid the false positives. Because we cannot rely on PAGE_OFFSET always being a compile-time constant, nor on it always being >0, we fall back to disabling the dma_index storage when there are not enough bits available. This leaves us in the situation we were in before the patch in the Fixes tag, but only on a subset of architecture configurations. This seems to be the best we can do until the transition to page types in complete for page_pool pages. v2: - Make sure there's at least 8 bits available and that the PAGE_OFFSET bit calculation doesn't wrap Link: https://lore.kernel.org/all/aMNJMFa5fDalFmtn@p100/ Fixes: ee62ce7a1d90 ("page_pool: Track DMA-mapped pages and unmap them when destroying the pool") Cc: stable(a)vger.kernel.org # 6.15+ Tested-by: Helge Deller <deller(a)gmx.de> Signed-off-by: Toke Høiland-Jørgensen <toke(a)redhat.com> --- include/linux/mm.h | 22 +++++++------ net/core/page_pool.c | 76 ++++++++++++++++++++++++++++++-------------- 2 files changed, 66 insertions(+), 32 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 1ae97a0b8ec7..0905eb6b55ec 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4159,14 +4159,13 @@ int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status); * since this value becomes part of PP_SIGNATURE; meaning we can just use the * space between the PP_SIGNATURE value (without POISON_POINTER_DELTA), and the * lowest bits of POISON_POINTER_DELTA. On arches where POISON_POINTER_DELTA is - * 0, we make sure that we leave the two topmost bits empty, as that guarantees - * we won't mistake a valid kernel pointer for a value we set, regardless of the - * VMSPLIT setting. + * 0, we use the lowest bit of PAGE_OFFSET as the boundary if that value is + * known at compile-time. * - * Altogether, this means that the number of bits available is constrained by - * the size of an unsigned long (at the upper end, subtracting two bits per the - * above), and the definition of PP_SIGNATURE (with or without - * POISON_POINTER_DELTA). + * If the value of PAGE_OFFSET is not known at compile time, or if it is too + * small to leave at least 8 bits available above PP_SIGNATURE, we define the + * number of bits to be 0, which turns off the DMA index tracking altogether + * (see page_pool_register_dma_index()). */ #define PP_DMA_INDEX_SHIFT (1 + __fls(PP_SIGNATURE - POISON_POINTER_DELTA)) #if POISON_POINTER_DELTA > 0 @@ -4175,8 +4174,13 @@ int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status); */ #define PP_DMA_INDEX_BITS MIN(32, __ffs(POISON_POINTER_DELTA) - PP_DMA_INDEX_SHIFT) #else -/* Always leave out the topmost two; see above. */ -#define PP_DMA_INDEX_BITS MIN(32, BITS_PER_LONG - PP_DMA_INDEX_SHIFT - 2) +/* Use the lowest bit of PAGE_OFFSET if there's at least 8 bits available; see above */ +#define PP_DMA_INDEX_MIN_OFFSET (1 << (PP_DMA_INDEX_SHIFT + 8)) +#define PP_DMA_INDEX_BITS ((__builtin_constant_p(PAGE_OFFSET) && \ + PAGE_OFFSET >= PP_DMA_INDEX_MIN_OFFSET && \ + !(PAGE_OFFSET & (PP_DMA_INDEX_MIN_OFFSET - 1))) ? \ + MIN(32, __ffs(PAGE_OFFSET) - PP_DMA_INDEX_SHIFT) : 0) + #endif #define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \ diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 492728f9e021..1a5edec485f1 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -468,11 +468,60 @@ page_pool_dma_sync_for_device(const struct page_pool *pool, } } +static int page_pool_register_dma_index(struct page_pool *pool, + netmem_ref netmem, gfp_t gfp) +{ + int err = 0; + u32 id; + + if (unlikely(!PP_DMA_INDEX_BITS)) + goto out; + + if (in_softirq()) + err = xa_alloc(&pool->dma_mapped, &id, netmem_to_page(netmem), + PP_DMA_INDEX_LIMIT, gfp); + else + err = xa_alloc_bh(&pool->dma_mapped, &id, netmem_to_page(netmem), + PP_DMA_INDEX_LIMIT, gfp); + if (err) { + WARN_ONCE(err != -ENOMEM, "couldn't track DMA mapping, please report to netdev@"); + goto out; + } + + netmem_set_dma_index(netmem, id); +out: + return err; +} + +static int page_pool_release_dma_index(struct page_pool *pool, + netmem_ref netmem) +{ + struct page *old, *page = netmem_to_page(netmem); + unsigned long id; + + if (unlikely(!PP_DMA_INDEX_BITS)) + return 0; + + id = netmem_get_dma_index(netmem); + if (!id) + return -1; + + if (in_softirq()) + old = xa_cmpxchg(&pool->dma_mapped, id, page, NULL, 0); + else + old = xa_cmpxchg_bh(&pool->dma_mapped, id, page, NULL, 0); + if (old != page) + return -1; + + netmem_set_dma_index(netmem, 0); + + return 0; +} + static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem, gfp_t gfp) { dma_addr_t dma; int err; - u32 id; /* Setup DMA mapping: use 'struct page' area for storing DMA-addr * since dma_addr_t can be either 32 or 64 bits and does not always fit @@ -491,18 +540,10 @@ static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem, gfp_t g goto unmap_failed; } - if (in_softirq()) - err = xa_alloc(&pool->dma_mapped, &id, netmem_to_page(netmem), - PP_DMA_INDEX_LIMIT, gfp); - else - err = xa_alloc_bh(&pool->dma_mapped, &id, netmem_to_page(netmem), - PP_DMA_INDEX_LIMIT, gfp); - if (err) { - WARN_ONCE(err != -ENOMEM, "couldn't track DMA mapping, please report to netdev@"); + err = page_pool_register_dma_index(pool, netmem, gfp); + if (err) goto unset_failed; - } - netmem_set_dma_index(netmem, id); page_pool_dma_sync_for_device(pool, netmem, pool->p.max_len); return true; @@ -680,8 +721,6 @@ void page_pool_clear_pp_info(netmem_ref netmem) static __always_inline void __page_pool_release_netmem_dma(struct page_pool *pool, netmem_ref netmem) { - struct page *old, *page = netmem_to_page(netmem); - unsigned long id; dma_addr_t dma; if (!pool->dma_map) @@ -690,15 +729,7 @@ static __always_inline void __page_pool_release_netmem_dma(struct page_pool *poo */ return; - id = netmem_get_dma_index(netmem); - if (!id) - return; - - if (in_softirq()) - old = xa_cmpxchg(&pool->dma_mapped, id, page, NULL, 0); - else - old = xa_cmpxchg_bh(&pool->dma_mapped, id, page, NULL, 0); - if (old != page) + if (page_pool_release_dma_index(pool, netmem)) return; dma = page_pool_get_dma_addr_netmem(netmem); @@ -708,7 +739,6 @@ static __always_inline void __page_pool_release_netmem_dma(struct page_pool *poo PAGE_SIZE << pool->p.order, pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING); page_pool_set_dma_addr_netmem(netmem, 0); - netmem_set_dma_index(netmem, 0); } /* Disconnects a page (from a page_pool). API users can have a need -- 2.51.0

15 hours, 25 minutes

[PATCH 0/2] Kconfig fixes for QCOM clk drivers when targeting ARCH=arm

by Nathan Chancellor

Hi all, This series resolves two new Kconfig warnings that I see in my test framework from an ARM configuration getting bumped to 6.17 and enabling these configurations in the process. --- Nathan Chancellor (2): clk: qcom: Fix SM_VIDEOCC_6350 dependencies clk: qcom: Fix dependencies of QCS_{DISP,GPU,VIDEO}CC_615 drivers/clk/qcom/Kconfig | 4 ++++ 1 file changed, 4 insertions(+) --- base-commit: 30bf3ec8cb6b2d2e2f8715388395cbd27cbe4fc9 change-id: 20250930-clk-qcom-kconfig-fixes-arm-3611dec03c3e Best regards, -- Nathan Chancellor <nathan(a)kernel.org>

16 hours, 50 minutes

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; > ), >

17 hours, 38 minutes

[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>

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Linux-stable-mirror October 2025