The patch titled
Subject: lib/test_kasan.c: use underlying string helpers
has been added to the -mm tree. Its filename is
kasan-test-use-underlying-string-helpers.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-test-use-underlying-string-helpers.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-test-use-underlying-string-helpers.patch
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------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: lib/test_kasan.c: use underlying string helpers
Calling memcmp() and memchr() with an intentional buffer overflow is now
caught at compile time:
In function 'memcmp',
inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2:
include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter)
263 | __read_overflow();
| ^~~~~~~~~~~~~~~~~
In function 'memchr',
inlined from 'kasan_memchr' at lib/test_kasan.c:872:2:
include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter)
277 | __read_overflow();
| ^~~~~~~~~~~~~~~~~
Change the kasan tests to wrap those inside of a noinline function
to prevent the compiler from noticing the bug and let kasan find
it at runtime.
Link: https://lkml.kernel.org/r/20211013150025.2875883-1-arnd@xxxxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Patricia Alfonso <trishalfonso@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_kasan.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
--- a/lib/test_kasan.c~kasan-test-use-underlying-string-helpers
+++ a/lib/test_kasan.c
@@ -831,6 +831,21 @@ static void kmem_cache_invalid_free(stru
kmem_cache_destroy(cache);
}
+/*
+ * noinline wrappers to prevent the compiler from noticing the overflow
+ * at compile time rather than having kasan catch it.
+ * */
+static noinline void *__kasan_memchr(const void *s, int c, size_t n)
+{
+ return memchr(s, c, n);
+}
+
+static noinline int __kasan_memcmp(const void *s1, const void *s2, size_t n)
+{
+ return memcmp(s1, s2, n);
+}
+
+
static void kasan_memchr(struct kunit *test)
{
char *ptr;
@@ -849,7 +864,7 @@ static void kasan_memchr(struct kunit *t
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
KUNIT_EXPECT_KASAN_FAIL(test,
- kasan_ptr_result = memchr(ptr, '1', size + 1));
+ kasan_ptr_result = __kasan_memchr(ptr, '1', size + 1));
kfree(ptr);
}
@@ -874,7 +889,7 @@ static void kasan_memcmp(struct kunit *t
memset(arr, 0, sizeof(arr));
KUNIT_EXPECT_KASAN_FAIL(test,
- kasan_int_result = memcmp(ptr, arr, size+1));
+ kasan_int_result = __kasan_memcmp(ptr, arr, size+1));
kfree(ptr);
}
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
kasan-test-use-underlying-string-helpers.patch
posix-acl-avoid-wempty-body-warning.patch
hfs-hfsplus-use-warn_on-for-sanity-check.patch
