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kasan/test: only do kmalloc_double_kzfree for generic mode

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kmalloc_double_kzfree() would corrupt kernel memory when the just freed
memory were allocated by another thread before the second call to
kfree_sensitive() and the new allocation tag happened to match the old
one.

This could not happen in GENERIC mode as it uses quarantine.

Link: https://lore.kernel.org/20260524031053.381776-1-wsw9603@163.com
Signed-off-by: Wang Wensheng <wsw9603@163.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Wang Wensheng 2026-05-24 11:10:53 +08:00 committed by Andrew Morton
parent 7e6cc35f52
commit 7c2ebe0fe0
1 changed files with 10 additions and 0 deletions
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10
mm/kasan/kasan_test_c.c
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@ -874,6 +874,16 @@ static void kmalloc_double_kzfree(struct kunit *test)
char *ptr;
size_t size = 16;
/*
* With the tag-based KASAN modes, if the memory happens to be
* reallocated between the two frees and the new allocation tag happens
* to match the old one, the second free will cause a memory corruption.
* Resolving https://bugzilla.kernel.org/show_bug.cgi?id=212177 would
* help to deal with this. With Generic KASAN, it's effectively
* impossible for the memory to get reallocated due to the quarantine.
*/
KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC);
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);