[Crash-utility] [PATCH 2/4] Fix gcc-11 compilation warning on symbols.c

[lijiang]

Hi, Kazu
Thank  you for the fix.

On Fri, Jul 22, 2022 at 12:45 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com>
wrote:

> Without the patch, the following gcc-11 compliation warning is emitted
> for symbols.c:
>
> symbols.c: In function 'cmd_p':
> symbols.c:7412:38: warning: writing 1 byte into a region of size 0
> [-Wstringop-overflow=]
>  7412 |                         *(cpuspec-1) = ':';
>       |                         ~~~~~~~~~~~~~^~~~~
>


I have one question about it:
This issue only appears in gcc-11 and earlier, I tested it with gcc-12, but
it disappeared. It's interesting.

In addition, a new warning was found(gcc-12), but it is not related to this
patch.
...
gcc -c -g -DX86_64 -DLZO -DGDB_10_2 -g -O2 lkcd_v1.c -DMCLX -Wall -O2
-Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
lkcd_v1.c: In function ‘dump_lkcd_environment_v1’:
lkcd_v1.c:252:20: warning: the comparison will always evaluate as ‘true’
for the address of ‘dh_panic_string’ will never be NULL [-Waddress]
  252 |                 dh && dh->dh_panic_string &&
      |                    ^~
In file included from lkcd_v1.c:21:
lkcd_vmdump_v1.h:108:30: note: ‘dh_panic_string’ declared here
  108 |         char                 dh_panic_string[DUMP_PANIC_LEN];
      |                              ^~~~~~~~~~~~~~~
gcc -c -g -DX86_64 -DLZO -DGDB_10_2 -g -O2 lkcd_v2_v3.c -DMCLX -Wall -O2
-Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
lkcd_v2_v3.c: In function ‘dump_lkcd_environment_v2_v3’:
lkcd_v2_v3.c:310:20: warning: the comparison will always evaluate as ‘true’
for the address of ‘dh_panic_string’ will never be NULL [-Waddress]
  310 |                 dh && dh->dh_panic_string &&
      |                    ^~
In file included from lkcd_v2_v3.c:21:
lkcd_vmdump_v2_v3.h:205:30: note: ‘dh_panic_string’ declared here
  205 |         char                 dh_panic_string[DUMP_PANIC_LEN];
      |                              ^~~~~~~~~~~~~~~
gcc -c -g -DX86_64 -DLZO -DGDB_10_2 -g -O2 lkcd_v5.c -DMCLX -Wall -O2
-Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
lkcd_v5.c: In function ‘dump_lkcd_environment_v5’:
lkcd_v5.c:273:20: warning: the comparison will always evaluate as ‘true’
for the address of ‘dh_panic_string’ will never be NULL [-Waddress]
  273 |                 dh && dh->dh_panic_string &&
      |                    ^~
In file included from lkcd_v5.c:20:
lkcd_dump_v5.h:163:30: note: ‘dh_panic_string’ declared here
  163 |         char                 dh_panic_string[DUMP_PANIC_LEN];
      |                              ^~~~~~~~~~~~~~~
gcc -c -g -DX86_64 -DLZO -DGDB_10_2 -g -O2 lkcd_v7.c -DMCLX -Wall -O2
-Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
lkcd_v7.c: In function ‘dump_lkcd_environment_v7’:
lkcd_v7.c:350:20: warning: the comparison will always evaluate as ‘true’
for the address of ‘dh_panic_string’ will never be NULL [-Waddress]
  350 |                 dh && dh->dh_panic_string &&
      |                    ^~
In file included from lkcd_v7.c:21:
lkcd_dump_v5.h:163:30: note: ‘dh_panic_string’ declared here
  163 |         char                 dh_panic_string[DUMP_PANIC_LEN];
      |                              ^~~~~~~~~~~~~~~
gcc -c -g -DX86_64 -DLZO -DGDB_10_2 -g -O2 lkcd_v8.c -DMCLX -Wall -O2
-Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
lkcd_v8.c: In function ‘dump_lkcd_environment_v8’:
lkcd_v8.c:546:20: warning: the comparison will always evaluate as ‘true’
for the address of ‘dh_panic_string’ will never be NULL [-Waddress]
  546 |                 dh && dh->dh_panic_string &&
      |                    ^~
In file included from lkcd_v8.c:23:
lkcd_dump_v8.h:165:30: note: ‘dh_panic_string’ declared here
  165 |         char                 dh_panic_string[DUMP_PANIC_LEN];
...

Thanks.
Lianbo


> Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> ---
>  symbols.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/symbols.c b/symbols.c
> index bee1faf..42c4eb4 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -7351,7 +7351,7 @@ cmd_p(void)
>         unsigned radix;
>         int do_load_module_filter;
>         char buf1[BUFSIZE];
> -       char *cpuspec;
> +       char *cpuspec, *p;
>
>         do_load_module_filter = radix = 0;
>
> @@ -7386,7 +7386,7 @@ cmd_p(void)
>          if (argerrs || !args[optind])
>                  cmd_usage(pc->curcmd, SYNOPSIS);
>
> -       cpuspec = strrchr(args[optind], ':');
> +       p = cpuspec = strrchr(args[optind], ':');
>         if (cpuspec)
>                 *cpuspec++ = NULLCHAR;
>
> @@ -7409,7 +7409,7 @@ cmd_p(void)
>                               sp->name);
>                 else
>                         /* maybe a valid C expression (e.g. ':') */
> -                       *(cpuspec-1) = ':';
> +                       *p = ':';
>         }
>
>         process_gdb_output(concat_args(buf1, 0, TRUE), radix,
> --
> 2.31.1
>
>
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