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kasan, mm: untag page address in free_reserved_area

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free_reserved_area() memsets the pages belonging to a given memory area.
As that memory hasn't been allocated via page_alloc, the KASAN tags that
those pages have are 0x00.  As the result the memset might result in a tag
mismatch.

Untag the address to avoid spurious faults.

Link: https://lkml.kernel.org/r/ebef6425f4468d063e2f09c1b62ccbb2236b71d3.1606161801.git.andreyknvl@google.com
Cc: Andrew Morton <[email protected]>
Signed-off-by: Vincenzo Frascino <[email protected]>
Signed-off-by: Andrey Konovalov <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Tested-by: Vincenzo Frascino <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Branislav Rankov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Evgenii Stepanov <[email protected]>
Cc: Kevin Brodsky <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Vincenzo Frascino
2020-12-22 12:55:07 -08:00
committed by Linus Torvalds
parent bad1e1c663
commit c746170d6a
1 changed files with 5 additions and 0 deletions
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mm/page_alloc.c
+5
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@@ -7671,6 +7671,11 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
* alias for the memset().
*/
direct_map_addr = page_address(page);
/*
* Perform a kasan-unchecked memset() since this memory
* has not been initialized.
*/
direct_map_addr = kasan_reset_tag(direct_map_addr);
if ((unsigned int)poison <= 0xFF)
memset(direct_map_addr, poison, PAGE_SIZE);