[merged mm-stable] kasan-test-only-do-kmalloc_double_kzfree-for-generic-mode.patch removed from -mm tree

[merged mm-stable] kasan-test-only-do-kmalloc_double_kzfree-for-generic-mode.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: kasan/test: only do kmalloc_double_kzfree for generic mode
has been removed from the -mm tree.  Its filename was
     kasan-test-only-do-kmalloc_double_kzfree-for-generic-mode.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Wang Wensheng <wsw9603@163.com>
Subject: kasan/test: only do kmalloc_double_kzfree for generic mode
Date: Sun, 24 May 2026 11:10:53 +0800

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>
---

 mm/kasan/kasan_test_c.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/mm/kasan/kasan_test_c.c~kasan-test-only-do-kmalloc_double_kzfree-for-generic-mode
+++ a/mm/kasan/kasan_test_c.c
@@ -874,6 +874,16 @@ static void kmalloc_double_kzfree(struct
 	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);
 
_

Patches currently in -mm which might be from wsw9603@163.com are