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Message-Id: <20220907233359.95875-1-keescook@chromium.org>
Date: Wed, 7 Sep 2022 16:33:59 -0700
From: Kees Cook <keescook@...omium.org>
To: Kees Cook <keescook@...omium.org>
Cc: kernel test robot <lkp@...el.com>, linux-kernel@...r.kernel.org,
linux-hardening@...r.kernel.org,
Wolfram Sang <wsa+renesas@...g-engineering.com>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] kunit/memcpy: Avoid pathological compile-time string size
The memcpy() KUnit tests are trying to sanity-check run-time behaviors,
but tripped compile-time warnings about a pathological condition of a
too-small buffer being used for input. Avoid this by explicitly resizing
the buffer, but leaving the string short. Avoid the following warning:
lib/memcpy_kunit.c: In function 'strtomem_test':
include/linux/string.h:303:42: warning: 'strnlen' specified bound 4 exceeds source size 3 [-Wstringop-overread]
303 | memcpy(dest, src, min(_dest_len, strnlen(src, _dest_len))); \
include/linux/minmax.h:32:39: note: in definition of macro '__cmp_once'
32 | typeof(y) unique_y = (y); \
| ^
include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
include/linux/string.h:303:27: note: in expansion of macro 'min'
303 | memcpy(dest, src, min(_dest_len, strnlen(src, _dest_len))); \
| ^~~
lib/memcpy_kunit.c:290:9: note: in expansion of macro 'strtomem'
290 | strtomem(wrap.output, input);
| ^~~~~~~~
lib/memcpy_kunit.c:275:27: note: source object allocated here
275 | static const char input[] = "hi";
| ^~~~~
Reported-by: kernel test robot <lkp@...el.com>
Link: https://lore.kernel.org/linux-mm/202209070728.o3stvgVt-lkp@intel.com
Fixes: 14fa26474621 ("string: Introduce strtomem() and strtomem_pad()")
Signed-off-by: Kees Cook <keescook@...omium.org>
---
lib/memcpy_kunit.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/memcpy_kunit.c b/lib/memcpy_kunit.c
index d22fa3838ee9..2b5cc70ac53f 100644
--- a/lib/memcpy_kunit.c
+++ b/lib/memcpy_kunit.c
@@ -272,7 +272,7 @@ static void memset_test(struct kunit *test)
static void strtomem_test(struct kunit *test)
{
- static const char input[] = "hi";
+ static const char input[sizeof(unsigned long)] = "hi";
static const char truncate[] = "this is too long";
struct {
unsigned long canary1;
--
2.34.1
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