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Commit 70b223ca authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Alistair Delva
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UPSTREAM: kasan, mm: perform untagged pointers comparison in krealloc 

(Upstream commit 772a2fa50ffb2f4282be8436da6e70530a2ac63c).

The krealloc function checks where the same buffer was reused or a new one
allocated by comparing kernel pointers.  Tag-based KASAN changes memory
tag on the krealloc'ed chunk of memory and therefore also changes the
pointer tag of the returned pointer.  Therefore we need to perform
comparison on untagged (with tags reset) pointers to check whether it's
the same memory region or not.

Link: http://lkml.kernel.org/r/14f6190d7846186a3506cd66d82446646fe65090.1544099024.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: default avatarDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Bug: 128674696
Change-Id: I1e64158a5a0d683fc19c76296bc5fa345639bf30
parent 1a640687

mm/slab_common.c

+1 −1
Original line number Diff line number Diff line
@@ -1513,7 +1513,7 @@ void *krealloc(const void *p, size_t new_size, gfp_t flags) 
	}



	ret = __do_krealloc(p, new_size, flags);

	if (ret && p != ret)

	if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))

		kfree(p);



	return ret;