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| author | Andrey Konovalov <andreyknvl@google.com> | 2020-12-22 12:02:17 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-22 12:55:08 -0800 |
| commit | aa1ef4d7b3f67f7f17aa4aa34f5ec513c7e4db6c (patch) | |
| tree | a076c42bb3c60ac54416144165b7bfc7cdc70d42 /mm/page_alloc.c | |
| parent | 4291e9ee618956eeae02b17f35b272193a6cda5a (diff) | |
| download | linux-aa1ef4d7b3f67f7f17aa4aa34f5ec513c7e4db6c.tar.bz2 | |
kasan, mm: reset tags when accessing metadata
Kernel allocator code accesses metadata for slab objects, that may lie
out-of-bounds of the object itself, or be accessed when an object is
freed. Such accesses trigger tag faults and lead to false-positive
reports with hardware tag-based KASAN.
Software KASAN modes disable instrumentation for allocator code via
KASAN_SANITIZE Makefile macro, and rely on kasan_enable/disable_current()
annotations which are used to ignore KASAN reports.
With hardware tag-based KASAN neither of those options are available, as
it doesn't use compiler instrumetation, no tag faults are ignored, and MTE
is disabled after the first one.
Instead, reset tags when accessing metadata (currently only for SLUB).
Link: https://lkml.kernel.org/r/a0f3cefbc49f34c843b664110842de4db28179d0.1606161801.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1887852fb934..7a2c89b21115 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1204,8 +1204,10 @@ static void kernel_init_free_pages(struct page *page, int numpages) /* s390's use of memset() could override KASAN redzones. */ kasan_disable_current(); - for (i = 0; i < numpages; i++) + for (i = 0; i < numpages; i++) { + page_kasan_tag_reset(page + i); clear_highpage(page + i); + } kasan_enable_current(); } |