kernel.git/mm/kmsan/hooks.c, branch linux-rolling-lts

mm/kmsan: fix kmsan kmalloc hook when no stack depots are allocated yet

2025-11-10T05:19:42Z

If no stack depot is allocated yet, due to masking out __GFP_RECLAIM flags kmsan called from kmalloc cannot allocate stack depot. kmsan fails to record origin and report issues. This may result in KMSAN failing to report issues. Reusing flags from kmalloc without modifying them should be safe for kmsan. For example, such chain of calls is possible: test_uninit_kmalloc -> kmalloc -> __kmalloc_cache_noprof -> slab_alloc_node -> slab_post_alloc_hook -> kmsan_slab_alloc -> kmsan_internal_poison_memory. Only when it is called in a context without flags present should __GFP_RECLAIM flags be masked. With this change all kmsan tests start working reliably. Eric reported: : Yes, KMSAN seems to be at least partially broken currently. Besides the : fact that the kmsan KUnit test is currently failing (which I reported at : https://lore.kernel.org/r/20250911175145.GA1376@sol), I've confirmed that : the poly1305 KUnit test causes a KMSAN warning with Aleksei's patch : applied but does not cause a warning without it. The warning did get : reached via syzbot somehow : (https://lore.kernel.org/r/751b3d80293a6f599bb07770afcef24f623c7da0.1761026343.git.xiaopei01@kylinos.cn/), : so KMSAN must still work in some cases. But it didn't work for me. Link: https://lkml.kernel.org/r/20250930115600.709776-2-aleksei.nikiforov@linux.ibm.com Link: https://lkml.kernel.org/r/20251022030213.GA35717@sol Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation") Signed-off-by: Aleksei Nikiforov Reviewed-by: Alexander Potapenko Tested-by: Eric Biggers Cc: Alexei Starovoitov Cc: Dmitriy Vyukov Cc: Ilya Leoshkevich Cc: Marco Elver Cc: Signed-off-by: Andrew Morton

kmsan: fix kmsan_handle_dma() to avoid false positives

2025-10-03T06:44:06Z

KMSAN reports an uninitialized value issue in dma_map_phys()[1]. This is a false positive caused by the way the virtual address is handled in kmsan_handle_dma(). Fix it by translating the physical address to a virtual address using phys_to_virt(). [1] BUG: KMSAN: uninit-value in dma_map_phys+0xdc5/0x1060 dma_map_phys+0xdc5/0x1060 dma_map_page_attrs+0xcf/0x130 e1000_xmit_frame+0x3c51/0x78f0 dev_hard_start_xmit+0x22f/0xa30 sch_direct_xmit+0x3b2/0xcf0 __dev_queue_xmit+0x3588/0x5e60 neigh_resolve_output+0x9c5/0xaf0 ip6_finish_output2+0x24e0/0x2d30 ip6_finish_output+0x903/0x10d0 ip6_output+0x331/0x600 mld_sendpack+0xb4a/0x1770 mld_ifc_work+0x1328/0x19b0 process_scheduled_works+0xb91/0x1d80 worker_thread+0xedf/0x1590 kthread+0xd5c/0xf00 ret_from_fork+0x1f5/0x4c0 ret_from_fork_asm+0x1a/0x30 Uninit was created at: __kmalloc_cache_noprof+0x8f5/0x16b0 syslog_print+0x9a/0xef0 do_syslog+0x849/0xfe0 __x64_sys_syslog+0x97/0x100 x64_sys_call+0x3cf8/0x3e30 do_syscall_64+0xd9/0xfa0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Bytes 0-89 of 90 are uninitialized Memory access of size 90 starts at ffff8880367ed000 CPU: 1 UID: 0 PID: 1552 Comm: kworker/1:2 Not tainted 6.17.0-next-20250929 #26 PREEMPT(none) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-5.fc42 04/01/2014 Workqueue: mld mld_ifc_work Fixes: 6eb1e769b2c1 ("kmsan: convert kmsan_handle_dma to use physical addresses") Signed-off-by: Shigeru Yoshida Reviewed-by: Jason Gunthorpe Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20251002051024.3096061-1-syoshida@redhat.com

kmsan: fix missed kmsan_handle_dma() signature conversion

2025-09-17T12:42:36Z

kmsan_handle_dma_sg() has call to kmsan_handle_dma() function which was missed during conversion to physical addresses. Update that caller too and fix the following compilation error: mm/kmsan/hooks.c:372:6: error: too many arguments to function call, expected 3, have 4 371 | kmsan_handle_dma(sg_page(item), item->offset, item->length, | ~~~~~~~~~~~~~~~~ 372 | dir); | ^~~ mm/kmsan/hooks.c:362:19: note: 'kmsan_handle_dma' declared here 362 | EXPORT_SYMBOL_GPL(kmsan_handle_dma); Fixes: 6eb1e769b2c1 ("kmsan: convert kmsan_handle_dma to use physical addresses") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202509170638.AMGNCMEE-lkp@intel.com/ Signed-off-by: Leon Romanovsky Reviewed-by: Jason Gunthorpe Reviewed-by: Alexander Potapenko Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/4b2d7d0175b30177733bbbd42bf979d77eb73c29.1758090947.git.leon@kernel.org

kmsan: convert kmsan_handle_dma to use physical addresses

2025-09-11T22:18:20Z

Convert the KMSAN DMA handling function from page-based to physical address-based interface. The refactoring renames kmsan_handle_dma() parameters from accepting (struct page *page, size_t offset, size_t size) to (phys_addr_t phys, size_t size). The existing semantics where callers are expected to provide only kmap memory is continued here. Reviewed-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/3557cbaf66e935bc794f37d2b891ef75cbf2c80c.1757423202.git.leonro@nvidia.com

kmsan: enter the runtime around kmsan_internal_memmove_metadata() call

2025-05-21T16:55:16Z

kmsan_internal_memmove_metadata() transitively calls stack_depot_save() (via kmsan_internal_chain_origin() and kmsan_save_stack_with_flags()), which may allocate memory. Guard it with kmsan_enter_runtime() and kmsan_leave_runtime() to avoid recursion. This bug was spotted by CONFIG_WARN_CAPABILITY_ANALYSIS=y Link: https://lkml.kernel.org/r/20250507160012.3311104-4-glider@google.com Signed-off-by: Alexander Potapenko Acked-by: Marco Elver Cc: Bart Van Assche Cc: Kent Overstreet Cc: Dmitriy Vyukov Cc: Ilya Leoshkevich Signed-off-by: Andrew Morton

kmsan: apply clang-format to files mm/kmsan/

2025-05-21T16:55:15Z

KMSAN source files are expected to be formatted with clang-format, fix some nits that slipped in. No functional change. Link: https://lkml.kernel.org/r/20250507160012.3311104-1-glider@google.com Signed-off-by: Alexander Potapenko Cc: Ilya Leoshkevich Cc: Bart van Assche Cc: Dmitriy Vyukov Cc: Kent Overstreet Cc: Macro Elver Signed-off-by: Andrew Morton

dma: kmsan: export kmsan_handle_dma() for modules

2025-03-06T05:36:14Z

kmsan_handle_dma() is used by virtio_ring() which can be built as a module. kmsan_handle_dma() needs to be exported otherwise building the virtio_ring fails. Export kmsan_handle_dma for modules. Link: https://lkml.kernel.org/r/20250218091411.MMS3wBN9@linutronix.de Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202502150634.qjxwSeJR-lkp@intel.com/ Fixes: 7ade4f10779c ("dma: kmsan: unpoison DMA mappings") Signed-off-by: Sebastian Andrzej Siewior Cc: Alexander Potapenko Cc: Dmitriy Vyukov Cc: Macro Elver Cc: Peter Zijlstra (Intel) Cc: Thomas Gleixner Cc: Signed-off-by: Andrew Morton

kmsan: do not pass NULL pointers as 0

2024-07-04T02:30:26Z

sparse complains about passing NULL pointers as 0. Fix all instances. Link: https://lkml.kernel.org/r/20240627145754.27333-3-iii@linux.ibm.com Signed-off-by: Ilya Leoshkevich Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202406272033.KejtfLkw-lkp@intel.com/ Reviewed-by: Alexander Potapenko Cc: Dmitry Vyukov Cc: Marco Elver Signed-off-by: Andrew Morton

kmsan: support SLAB_POISON

2024-07-04T02:30:22Z

Avoid false KMSAN negatives with SLUB_DEBUG by allowing kmsan_slab_free() to poison the freed memory, and by preventing init_object() from unpoisoning new allocations by using __memset(). There are two alternatives to this approach. First, init_object() can be marked with __no_sanitize_memory. This annotation should be used with great care, because it drops all instrumentation from the function, and any shadow writes will be lost. Even though this is not a concern with the current init_object() implementation, this may change in the future. Second, kmsan_poison_memory() calls may be added after memset() calls. The downside is that init_object() is called from free_debug_processing(), in which case poisoning will erase the distinction between simply uninitialized memory and UAF. Link: https://lkml.kernel.org/r/20240621113706.315500-14-iii@linux.ibm.com Signed-off-by: Ilya Leoshkevich Reviewed-by: Alexander Potapenko Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Heiko Carstens Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Cc: Marco Elver Cc: Mark Rutland Cc: Masami Hiramatsu (Google) Cc: Pekka Enberg Cc: Roman Gushchin Cc: Steven Rostedt (Google) Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Signed-off-by: Andrew Morton

kmsan: allow disabling KMSAN checks for the current task

2024-07-04T02:30:22Z

Like for KASAN, it's useful to temporarily disable KMSAN checks around, e.g., redzone accesses. Introduce kmsan_disable_current() and kmsan_enable_current(), which are similar to their KASAN counterparts. Make them reentrant in order to handle memory allocations in interrupt context. Repurpose the allow_reporting field for this. Link: https://lkml.kernel.org/r/20240621113706.315500-12-iii@linux.ibm.com Signed-off-by: Ilya Leoshkevich Reviewed-by: Alexander Potapenko Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Heiko Carstens Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Cc: Marco Elver Cc: Mark Rutland Cc: Masami Hiramatsu (Google) Cc: Pekka Enberg Cc: Roman Gushchin Cc: Steven Rostedt (Google) Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Signed-off-by: Andrew Morton