From 7c2ebe0fe06e84a5a1fcbc358111735080bdb141 Mon Sep 17 00:00:00 2001 From: Wang Wensheng Date: Sun, 24 May 2026 11:10:53 +0800 Subject: [PATCH] kasan/test: only do kmalloc_double_kzfree for generic mode 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 Reviewed-by: Andrey Konovalov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Vincenzo Frascino Signed-off-by: Andrew Morton --- mm/kasan/kasan_test_c.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c index 32d06cbf6a31..3f4ed29178b3 100644 --- a/mm/kasan/kasan_test_c.c +++ b/mm/kasan/kasan_test_c.c @@ -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);