Messages in this thread Patch in this message | | | Date | Fri, 14 May 2021 09:22:28 +0200 | Subject | [PATCH] kasan: slab: always reset the tag in get_freepointer_safe() | From | Alexander Potapenko <> |
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With CONFIG_DEBUG_PAGEALLOC enabled, the kernel should also untag the object pointer, as done in get_freepointer().
Failing to do so reportedly leads to SLUB freelist corruptions that manifest as boot-time crashes.
Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Elliot Berman <eberman@codeaurora.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Alexander Potapenko <glider@google.com> --- mm/slub.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/mm/slub.c b/mm/slub.c index feda53ae62ba..9a4f59e5b0c2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -301,6 +301,7 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) if (!debug_pagealloc_enabled_static()) return get_freepointer(s, object); + object = kasan_reset_tag(object); freepointer_addr = (unsigned long)object + s->offset; copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p)); return freelist_ptr(s, p, freepointer_addr); -- 2.31.1.751.gd2f1c929bd-goog
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