kernel/linux.git/mm/kmsan, branch v6.1.168

mm: kmsan: fix poisoning of high-order non-compound pages

2026-02-06T15:44:19+00:00

[ Upstream commit 4795d205d78690a46b60164f44b8bb7b3e800865 ] kmsan_free_page() is called by the page allocator's free_pages_prepare() during page freeing. Its job is to poison all the memory covered by the page. It can be called with an order-0 page, a compound high-order page or a non-compound high-order page. But page_size() only works for order-0 and compound pages. For a non-compound high-order page it will incorrectly return PAGE_SIZE. The implication is that the tail pages of a high-order non-compound page do not get poisoned at free, so any invalid access while they are free could go unnoticed. It looks like the pages will be poisoned again at allocation time, so that would bookend the window. Fix this by using the order parameter to calculate the size. Link: https://lkml.kernel.org/r/20260104134348.3544298-1-ryan.roberts@arm.com Fixes: b073d7f8aee4 ("mm: kmsan: maintain KMSAN metadata for page operations") Signed-off-by: Ryan Roberts Reviewed-by: Alexander Potapenko Tested-by: Alexander Potapenko Cc: Dmitriy Vyukov Cc: Dmitry Vyukov Cc: Marco Elver Cc: Ryan Roberts Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

kmsan: fix out-of-bounds access to shadow memory

2025-10-02T11:40:43+00:00

[ Upstream commit 85e1ff61060a765d91ee62dc5606d4d547d9d105 ] Running sha224_kunit on a KMSAN-enabled kernel results in a crash in kmsan_internal_set_shadow_origin(): BUG: unable to handle page fault for address: ffffbc3840291000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 1810067 P4D 1810067 PUD 192d067 PMD 3c17067 PTE 0 Oops: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 81 Comm: kunit_try_catch Tainted: G N 6.17.0-rc3 #10 PREEMPT(voluntary) Tainted: [N]=TEST Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 RIP: 0010:kmsan_internal_set_shadow_origin+0x91/0x100 [...] Call Trace: __msan_memset+0xee/0x1a0 sha224_final+0x9e/0x350 test_hash_buffer_overruns+0x46f/0x5f0 ? kmsan_get_shadow_origin_ptr+0x46/0xa0 ? __pfx_test_hash_buffer_overruns+0x10/0x10 kunit_try_run_case+0x198/0xa00 This occurs when memset() is called on a buffer that is not 4-byte aligned and extends to the end of a guard page, i.e. the next page is unmapped. The bug is that the loop at the end of kmsan_internal_set_shadow_origin() accesses the wrong shadow memory bytes when the address is not 4-byte aligned. Since each 4 bytes are associated with an origin, it rounds the address and size so that it can access all the origins that contain the buffer. However, when it checks the corresponding shadow bytes for a particular origin, it incorrectly uses the original unrounded shadow address. This results in reads from shadow memory beyond the end of the buffer's shadow memory, which crashes when that memory is not mapped. To fix this, correctly align the shadow address before accessing the 4 shadow bytes corresponding to each origin. Link: https://lkml.kernel.org/r/20250911195858.394235-1-ebiggers@kernel.org Fixes: 2ef3cec44c60 ("kmsan: do not wipe out origin when doing partial unpoisoning") Signed-off-by: Eric Biggers Tested-by: Alexander Potapenko Reviewed-by: Alexander Potapenko Cc: Dmitriy Vyukov Cc: Marco Elver Cc: Signed-off-by: Andrew Morton [ Adjust context in tests ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

dma: kmsan: export kmsan_handle_dma() for modules

2025-03-13T11:53:15+00:00

commit 19fac3c93991502a22c5132824c40b6a2e64b136 upstream. 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 Signed-off-by: Greg Kroah-Hartman

kmsan: do not wipe out origin when doing partial unpoisoning

2024-06-16T11:41:38+00:00

commit 2ef3cec44c60ae171b287db7fc2aa341586d65ba upstream. As noticed by Brian, KMSAN should not be zeroing the origin when unpoisoning parts of a four-byte uninitialized value, e.g.: char a[4]; kmsan_unpoison_memory(a, 1); This led to false negatives, as certain poisoned values could receive zero origins, preventing those values from being reported. To fix the problem, check that kmsan_internal_set_shadow_origin() writes zero origins only to slots which have zero shadow. Link: https://lkml.kernel.org/r/20240528104807.738758-1-glider@google.com Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core") Signed-off-by: Alexander Potapenko Reported-by: Brian Johannesmeyer Link: https://lore.kernel.org/lkml/20240524232804.1984355-1-bjohannesmeyer@gmail.com/T/ Reviewed-by: Marco Elver Tested-by: Brian Johannesmeyer Cc: Dmitry Vyukov Cc: Kees Cook Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm: kmsan: handle alloc failures in kmsan_vmap_pages_range_noflush()

2023-04-26T12:28:41+00:00

commit 47ebd0310e89c087f56e58c103c44b72a2f6b216 upstream. As reported by Dipanjan Das, when KMSAN is used together with kernel fault injection (or, generally, even without the latter), calls to kcalloc() or __vmap_pages_range_noflush() may fail, leaving the metadata mappings for the virtual mapping in an inconsistent state. When these metadata mappings are accessed later, the kernel crashes. To address the problem, we return a non-zero error code from kmsan_vmap_pages_range_noflush() in the case of any allocation/mapping failure inside it, and make vmap_pages_range_noflush() return an error if KMSAN fails to allocate the metadata. This patch also removes KMSAN_WARN_ON() from vmap_pages_range_noflush(), as these allocation failures are not fatal anymore. Link: https://lkml.kernel.org/r/20230413131223.4135168-1-glider@google.com Fixes: b073d7f8aee4 ("mm: kmsan: maintain KMSAN metadata for page operations") Signed-off-by: Alexander Potapenko Reported-by: Dipanjan Das Link: https://lore.kernel.org/linux-mm/CANX2M5ZRrRA64k0hOif02TjmY9kbbO2aCBPyq79es34RXZ=cAw@mail.gmail.com/ Reviewed-by: Marco Elver Cc: Christoph Hellwig Cc: Dmitry Vyukov Cc: Uladzislau Rezki (Sony) Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm: kmsan: handle alloc failures in kmsan_ioremap_page_range()

2023-04-26T12:28:41+00:00

commit fdea03e12aa2a44a7bb34144208be97fc25dfd90 upstream. Similarly to kmsan_vmap_pages_range_noflush(), kmsan_ioremap_page_range() must also properly handle allocation/mapping failures. In the case of such, it must clean up the already created metadata mappings and return an error code, so that the error can be propagated to ioremap_page_range(). Without doing so, KMSAN may silently fail to bring the metadata for the page range into a consistent state, which will result in user-visible crashes when trying to access them. Link: https://lkml.kernel.org/r/20230413131223.4135168-2-glider@google.com Fixes: b073d7f8aee4 ("mm: kmsan: maintain KMSAN metadata for page operations") Signed-off-by: Alexander Potapenko Reported-by: Dipanjan Das Link: https://lore.kernel.org/linux-mm/CANX2M5ZRrRA64k0hOif02TjmY9kbbO2aCBPyq79es34RXZ=cAw@mail.gmail.com/ Reviewed-by: Marco Elver Cc: Christoph Hellwig Cc: Dmitry Vyukov Cc: Uladzislau Rezki (Sony) Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

kmsan: include linux/vmalloc.h

2023-01-04T10:28:59+00:00

commit aaa746ad8b30f38ef89a301faf339ef1c19cf33a upstream. This is needed for the vmap/vunmap declarations: mm/kmsan/kmsan_test.c:316:9: error: implicit declaration of function 'vmap' is invalid in C99 [-Werror,-Wimplicit-function-declaration] vbuf = vmap(pages, npages, VM_MAP, PAGE_KERNEL); ^ mm/kmsan/kmsan_test.c:316:29: error: use of undeclared identifier 'VM_MAP' vbuf = vmap(pages, npages, VM_MAP, PAGE_KERNEL); ^ mm/kmsan/kmsan_test.c:322:3: error: implicit declaration of function 'vunmap' is invalid in C99 [-Werror,-Wimplicit-function-declaration] vunmap(vbuf); ^ Link: https://lkml.kernel.org/r/20221215163046.4079767-1-arnd@kernel.org Fixes: 8ed691b02ade ("kmsan: add tests for KMSAN") Signed-off-by: Arnd Bergmann Reviewed-by: Alexander Potapenko Cc: Dmitry Vyukov Cc: Marco Elver Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

kmsan: export kmsan_handle_urb

2023-01-04T10:28:59+00:00

commit 7ba594d700998bafa96a75360d2e060aa39156d2 upstream. USB support can be in a loadable module, and this causes a link failure with KMSAN: ERROR: modpost: "kmsan_handle_urb" [drivers/usb/core/usbcore.ko] undefined! Export the symbol so it can be used by this module. Link: https://lkml.kernel.org/r/20221215162710.3802378-1-arnd@kernel.org Fixes: 553a80188a5d ("kmsan: handle memory sent to/from USB") Signed-off-by: Arnd Bergmann Reviewed-by: Alexander Potapenko Cc: Dmitry Vyukov Cc: Marco Elver Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

kmsan: core: kmsan_in_runtime() should return true in NMI context

2022-11-08T23:57:24+00:00

Without that, every call to __msan_poison_alloca() in NMI may end up allocating memory, which is NMI-unsafe. Link: https://lkml.kernel.org/r/20221102110611.1085175-1-glider@google.com Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/ Signed-off-by: Alexander Potapenko Acked-by: Peter Zijlstra (Intel) Cc: Dmitry Vyukov Cc: Marco Elver Cc: Borislav Petkov Cc: Dave Hansen Cc: Ingo Molnar Cc: Kees Cook Cc: Masahiro Yamada Cc: Nick Desaulniers Cc: Thomas Gleixner Signed-off-by: Andrew Morton

x86: fortify: kmsan: fix KMSAN fortify builds

2022-10-28T20:37:23+00:00

Ensure that KMSAN builds replace memset/memcpy/memmove calls with the respective __msan_XXX functions, and that none of the macros are redefined twice. This should allow building kernel with both CONFIG_KMSAN and CONFIG_FORTIFY_SOURCE. Link: https://lkml.kernel.org/r/20221024212144.2852069-5-glider@google.com Link: https://github.com/google/kmsan/issues/89 Signed-off-by: Alexander Potapenko Reported-by: Tamas K Lengyel Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Kees Cook Signed-off-by: Andrew Morton