* [ammarfaizi2-block:rostedt/linux-trace/ftrace/core 33/41] include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length
@ 2022-03-08 13:15 kernel test robot
2022-03-08 15:36 ` Steven Rostedt
0 siblings, 1 reply; 2+ messages in thread
From: kernel test robot @ 2022-03-08 13:15 UTC (permalink / raw)
To: Steven Rostedt (Google); +Cc: kbuild-all, GNU/Weeb Mailing List, linux-kernel
tree: https://github.com/ammarfaizi2/linux-block rostedt/linux-trace/ftrace/core
head: 7ab34c09507b05b91207c596490e3b6c935b7b97
commit: 9f8e5aee93ed2482638d577a56806b455084b595 [33/41] tracing: Fix allocation of last_cmd in last_cmd_set()
config: x86_64-rhel-8.3 (https://download.01.org/0day-ci/archive/20220308/[email protected]/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/ammarfaizi2/linux-block/commit/9f8e5aee93ed2482638d577a56806b455084b595
git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
git fetch --no-tags ammarfaizi2-block rostedt/linux-trace/ftrace/core
git checkout 9f8e5aee93ed2482638d577a56806b455084b595
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/trace/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
In file included from include/linux/string.h:253,
from include/linux/bitmap.h:11,
from include/linux/cpumask.h:12,
from arch/x86/include/asm/cpumask.h:5,
from arch/x86/include/asm/msr.h:11,
from arch/x86/include/asm/processor.h:22,
from arch/x86/include/asm/timex.h:5,
from include/linux/timex.h:65,
from include/linux/time32.h:13,
from include/linux/time.h:60,
from include/linux/stat.h:19,
from include/linux/module.h:13,
from kernel/trace/trace_events_hist.c:8:
In function 'strncat',
inlined from 'last_cmd_set' at kernel/trace/trace_events_hist.c:760:2,
inlined from 'event_hist_trigger_parse' at kernel/trace/trace_events_hist.c:6191:3:
>> include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length [-Wstringop-truncation]
47 | #define __underlying_strncat __builtin_strncat
| ^
include/linux/fortify-string.h:191:10: note: in expansion of macro '__underlying_strncat'
191 | return __underlying_strncat(p, q, count);
| ^~~~~~~~~~~~~~~~~~~~
kernel/trace/trace_events_hist.c: In function 'event_hist_trigger_parse':
include/linux/fortify-string.h:46:29: note: length computed here
46 | #define __underlying_strlen __builtin_strlen
| ^
include/linux/fortify-string.h:102:10: note: in expansion of macro '__underlying_strlen'
102 | return __underlying_strlen(p);
| ^~~~~~~~~~~~~~~~~~~
vim +/__builtin_strncat +47 include/linux/fortify-string.h
3009f891bb9f32 Kees Cook 2021-08-02 26
a28a6e860c6cf2 Francis Laniel 2021-02-25 27 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
a28a6e860c6cf2 Francis Laniel 2021-02-25 28 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
a28a6e860c6cf2 Francis Laniel 2021-02-25 29 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
a28a6e860c6cf2 Francis Laniel 2021-02-25 30 extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25 31 extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
a28a6e860c6cf2 Francis Laniel 2021-02-25 32 extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
a28a6e860c6cf2 Francis Laniel 2021-02-25 33 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
a28a6e860c6cf2 Francis Laniel 2021-02-25 34 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25 35 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
a28a6e860c6cf2 Francis Laniel 2021-02-25 36 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
a28a6e860c6cf2 Francis Laniel 2021-02-25 37 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25 38 #else
a28a6e860c6cf2 Francis Laniel 2021-02-25 39 #define __underlying_memchr __builtin_memchr
a28a6e860c6cf2 Francis Laniel 2021-02-25 40 #define __underlying_memcmp __builtin_memcmp
a28a6e860c6cf2 Francis Laniel 2021-02-25 41 #define __underlying_memcpy __builtin_memcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25 42 #define __underlying_memmove __builtin_memmove
a28a6e860c6cf2 Francis Laniel 2021-02-25 43 #define __underlying_memset __builtin_memset
a28a6e860c6cf2 Francis Laniel 2021-02-25 44 #define __underlying_strcat __builtin_strcat
a28a6e860c6cf2 Francis Laniel 2021-02-25 45 #define __underlying_strcpy __builtin_strcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25 46 #define __underlying_strlen __builtin_strlen
a28a6e860c6cf2 Francis Laniel 2021-02-25 @47 #define __underlying_strncat __builtin_strncat
a28a6e860c6cf2 Francis Laniel 2021-02-25 48 #define __underlying_strncpy __builtin_strncpy
a28a6e860c6cf2 Francis Laniel 2021-02-25 49 #endif
a28a6e860c6cf2 Francis Laniel 2021-02-25 50
:::::: The code at line 47 was first introduced by commit
:::::: a28a6e860c6cf231cf3c5171c75c342adcd00406 string.h: move fortified functions definitions in a dedicated header.
:::::: TO: Francis Laniel <[email protected]>
:::::: CC: Linus Torvalds <[email protected]>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [ammarfaizi2-block:rostedt/linux-trace/ftrace/core 33/41] include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length
2022-03-08 13:15 [ammarfaizi2-block:rostedt/linux-trace/ftrace/core 33/41] include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length kernel test robot
@ 2022-03-08 15:36 ` Steven Rostedt
0 siblings, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2022-03-08 15:36 UTC (permalink / raw)
To: kernel test robot
Cc: kbuild-all, GNU/Weeb Mailing List, linux-kernel, Tom Zanussi
On Tue, 8 Mar 2022 21:15:29 +0800
kernel test robot <[email protected]> wrote:
> All warnings (new ones prefixed by >>):
>
> In file included from include/linux/string.h:253,
> from include/linux/bitmap.h:11,
> from include/linux/cpumask.h:12,
> from arch/x86/include/asm/cpumask.h:5,
> from arch/x86/include/asm/msr.h:11,
> from arch/x86/include/asm/processor.h:22,
> from arch/x86/include/asm/timex.h:5,
> from include/linux/timex.h:65,
> from include/linux/time32.h:13,
> from include/linux/time.h:60,
> from include/linux/stat.h:19,
> from include/linux/module.h:13,
> from kernel/trace/trace_events_hist.c:8:
> In function 'strncat',
> inlined from 'last_cmd_set' at kernel/trace/trace_events_hist.c:760:2,
> inlined from 'event_hist_trigger_parse' at kernel/trace/trace_events_hist.c:6191:3:
> >> include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length [-Wstringop-truncation]
> 47 | #define __underlying_strncat __builtin_strncat
> | ^
> include/linux/fortify-string.h:191:10: note: in expansion of macro '__underlying_strncat'
> 191 | return __underlying_strncat(p, q, count);
> | ^~~~~~~~~~~~~~~~~~~~
> kernel/trace/trace_events_hist.c: In function 'event_hist_trigger_parse':
> include/linux/fortify-string.h:46:29: note: length computed here
> 46 | #define __underlying_strlen __builtin_strlen
> | ^
> include/linux/fortify-string.h:102:10: note: in expansion of macro '__underlying_strlen'
> 102 | return __underlying_strlen(p);
> | ^~~~~~~~~~~~~~~~~~~
I see my mistake. The code it's talking about is this:
len = sizeof(HIST_PREFIX) + strlen(str) + 1;
kfree(last_cmd);
last_cmd = kzalloc(len, GFP_KERNEL);
if (!last_cmd)
return;
strcpy(last_cmd, HIST_PREFIX);
len -= sizeof(HIST_PREFIX) + 1;
strncat(last_cmd, str, len);
Where according to the man page of strncat:
If src contains n or more bytes, strncat() writes n+1 bytes to dest (n
from src plus the terminating null byte). Therefore, the size of dest
must be at least strlen(dest)+n+1.
The above did: len -= sizeof(HIST_PREFIX) + 1; when it meant to do:
len -= strlen(HIST_PREFX) + 1
Or it could just do:
len -= sizeof(HIST_PREFIX)
as sizeof(HIST_PREFIX) contains the nul byte.
Heck, the allocation could be:
len = sizeof(HIST_PREFIX) + strlen(str);
As the sizeof already contains the nul byte.
Will fix.
Thanks,
-- Steve
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-03-08 13:15 [ammarfaizi2-block:rostedt/linux-trace/ftrace/core 33/41] include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length kernel test robot
2022-03-08 15:36 ` Steven Rostedt
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