[PATCH AUTOSEL 5.13 86/88] kasan: test: clean up ksize_uaf

From: Sasha Levin
Date: Thu Sep 09 2021 - 20:54:32 EST

From: Andrey Konovalov <andreyknvl@xxxxxxxxx>

[ Upstream commit b38fcca339dbcf680c9e43054502608fabc81508 ]

Some KASAN tests use global variables to store function returns values so
that the compiler doesn't optimize away these functions.

ksize_uaf() doesn't call any functions, so it doesn't need to use
kasan_int_result. Use volatile accesses instead, to be consistent with
other similar tests.

Link: https://lkml.kernel.org/r/a1fc34faca4650f4a6e4dfb3f8d8d82c82eb953a.1628779805.git.andreyknvl@xxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
lib/test_kasan.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index c8ca85fd5e16..7a02ecc63b7b 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -726,8 +726,8 @@ static void ksize_uaf(struct kunit *test)

KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr));
- KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result = *ptr);
- KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result = *(ptr + size));
+ KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]);
+ KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);

static void kasan_stack_oob(struct kunit *test)