@@ -411,7 +411,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
* must be discoverable by the compiler.
*/
#define strtomem_pad(dest, src, pad) do { \
- const size_t _dest_len = __builtin_object_size(dest, 1); \
+ const size_t _dest_len = __must_be_char_array(dest) + \
+ ARRAY_SIZE(dest); \
const size_t _src_len = __builtin_object_size(src, 1); \
\
BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \
@@ -434,7 +435,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
* must be discoverable by the compiler.
*/
#define strtomem(dest, src) do { \
- const size_t _dest_len = __builtin_object_size(dest, 1); \
+ const size_t _dest_len = __must_be_char_array(dest) + \
+ ARRAY_SIZE(dest); \
const size_t _src_len = __builtin_object_size(src, 1); \
\
BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \
@@ -453,7 +455,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
* Note that sizes of @dest and @src must be known at compile-time.
*/
#define memtostr(dest, src) do { \
- const size_t _dest_len = __builtin_object_size(dest, 1); \
+ const size_t _dest_len = __must_be_char_array(dest) + \
+ ARRAY_SIZE(dest); \
const size_t _src_len = __builtin_object_size(src, 1); \
const size_t _src_chars = strnlen(src, _src_len); \
const size_t _copy_len = min(_dest_len - 1, _src_chars); \
@@ -478,7 +481,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
* Note that sizes of @dest and @src must be known at compile-time.
*/
#define memtostr_pad(dest, src) do { \
- const size_t _dest_len = __builtin_object_size(dest, 1); \
+ const size_t _dest_len = __must_be_char_array(dest) + \
+ ARRAY_SIZE(dest); \
const size_t _src_len = __builtin_object_size(src, 1); \
const size_t _src_chars = strnlen(src, _src_len); \
const size_t _copy_len = min(_dest_len - 1, _src_chars); \
The destination argument of memtostr*() and strtomem*() must be a fixed-size char array at compile time, so there is no need to use __builtin_object_size() (which is useful for when an argument is either a pointer or unknown). Instead use ARRAY_SIZE(), which has the benefit of working around a bug in Clang (fixed[1] in 15+) that got __builtin_object_size() wrong sometimes. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202501310832.kiAeOt2z-lkp@intel.com/ Suggested-by: Kent Overstreet <kent.overstreet@linux.dev> Link: https://github.com/llvm/llvm-project/commit/d8e0a6d5e9dd2311641f9a8a5d2bf90829951ddc [1] Signed-off-by: Kees Cook <kees@kernel.org> --- Cc: Suren Baghdasaryan <surenb@google.com> Cc: nathan@kernel.org Cc: Andy Shevchenko <andy@kernel.org> Cc: linux-hardening@vger.kernel.org --- include/linux/string.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)