include/linux/fortify-string.h:27:33: warning: '__builtin_strncpy' output truncated copying between 0 and 32 bytes from a string of length 32

From: kernel test robot
Date: Tue Sep 28 2021 - 07:34:00 EST


tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 0513e464f9007b70b96740271a948ca5ab6e7dd7
commit: a28a6e860c6cf231cf3c5171c75c342adcd00406 string.h: move fortified functions definitions in a dedicated header.
date: 7 months ago
config: arm-randconfig-r001-20210928 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a28a6e860c6cf231cf3c5171c75c342adcd00406
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout a28a6e860c6cf231cf3c5171c75c342adcd00406
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arm

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

In file included from include/linux/string.h:269,
from include/linux/bitmap.h:9,
from include/linux/cpumask.h:12,
from include/linux/smp.h:13,
from include/linux/lockdep.h:14,
from include/linux/spinlock.h:59,
from include/linux/mmzone.h:8,
from include/linux/gfp.h:6,
from include/linux/umh.h:4,
from include/linux/kmod.h:9,
from include/linux/module.h:16,
from lib/test_hexdump.c:8:
In function 'strncpy',
inlined from 'test_hexdump_prepare_test.constprop' at lib/test_hexdump.c:116:3:
>> include/linux/fortify-string.h:27:33: warning: '__builtin_strncpy' output truncated copying between 0 and 32 bytes from a string of length 32 [-Wstringop-truncation]
27 | #define __underlying_strncpy __builtin_strncpy
| ^
include/linux/fortify-string.h:38:16: note: in expansion of macro '__underlying_strncpy'
38 | return __underlying_strncpy(p, q, size);
| ^~~~~~~~~~~~~~~~~~~~


vim +/__builtin_strncpy +27 include/linux/fortify-string.h

4
5
6 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
7 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
8 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
9 extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
10 extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
11 extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
12 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
13 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
14 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
15 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
16 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
17 #else
18 #define __underlying_memchr __builtin_memchr
19 #define __underlying_memcmp __builtin_memcmp
20 #define __underlying_memcpy __builtin_memcpy
21 #define __underlying_memmove __builtin_memmove
22 #define __underlying_memset __builtin_memset
23 #define __underlying_strcat __builtin_strcat
24 #define __underlying_strcpy __builtin_strcpy
25 #define __underlying_strlen __builtin_strlen
26 #define __underlying_strncat __builtin_strncat
> 27 #define __underlying_strncpy __builtin_strncpy
28 #endif
29

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip