The patch titled
Subject: kasan: adapt kmalloc_uaf2 test to HW_TAGS mode
has been added to the -mm tree. Its filename is
kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan: adapt kmalloc_uaf2 test to HW_TAGS mode
In the kmalloc_uaf2() test, the pointers to the two allocated memory
blocks might happen to be the same, and the test will fail. With the
software tag-based mode, the probability of the that is 1/254, so it's
hard to observe the failure. For the hardware tag-based mode though,
the probablity is 1/14, which is quite noticable.
Allow up to 16 attempts at generating different tags for the tag-based
modes.
Link: https://linux-review.googlesource.com/id/Ibfa458ef2804ff465d8eb07434a300bf36388d55
Link: https://lkml.kernel.org/r/9cd5cf2f633dcbf55cab801cd26845d2b075cec7.1610733117.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_kasan.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/lib/test_kasan.c~kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode
+++ a/lib/test_kasan.c
@@ -382,7 +382,9 @@ static void kmalloc_uaf2(struct kunit *t
{
char *ptr1, *ptr2;
size_t size = 43;
+ int counter = 0;
+again:
ptr1 = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
@@ -391,6 +393,15 @@ static void kmalloc_uaf2(struct kunit *t
ptr2 = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
+ /*
+ * For tag-based KASAN ptr1 and ptr2 tags might happen to be the same.
+ * Allow up to 16 attempts at generating different tags.
+ */
+ if (!IS_ENABLED(CONFIG_KASAN_GENERIC) && ptr1 == ptr2 && counter++ < 16) {
+ kfree(ptr2);
+ goto again;
+ }
+
KUNIT_EXPECT_KASAN_FAIL(test, ptr1[40] = 'x');
KUNIT_EXPECT_PTR_NE(test, ptr1, ptr2);
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-fix-hw_tags-boot-parameters.patch
kasan-prefix-global-functions-with-kasan_.patch
kasan-clarify-hw_tags-impact-on-tbi.patch
kasan-clean-up-comments-in-tests.patch
kasan-add-macros-to-simplify-checking-test-constraints.patch
kasan-add-match-all-tag-tests.patch
kasan-arm64-allow-using-kunit-tests-with-hw_tags-mode.patch
kasan-rename-config_test_kasan_module.patch
kasan-add-compiler-barriers-to-kunit_expect_kasan_fail.patch
kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode.patch
kasan-fix-memory-corruption-in-kasan_bitops_tags-test.patch
kasan-move-_ret_ip_-to-inline-wrappers.patch
kasan-fix-bug-detection-via-ksize-for-hw_tags-mode.patch
kasan-add-proper-page-allocator-tests.patch
kasan-add-a-test-for-kmem_cache_alloc-free_bulk.patch
kasan-dont-run-tests-when-kasan-is-not-enabled.patch
