On Mon, May 27, 2019 at 5:38 PM Arnaldo Carvalho de Melo
<a...@kernel.org> wrote:
>
> From: Shawn Landden <sh...@git.icu>
>
> This strncat() is safe because the buffer was allocated with zalloc(),
> however gcc doesn't know that. Since the string always has 4 non-null
> bytes, just use memcpy() here.
>
> CC /home/shawn/linux/tools/perf/util/data-convert-bt.o
> In file included from /usr/include/string.h:494,
> from
> /home/shawn/linux/tools/lib/traceevent/event-parse.h:27,
> from util/data-convert-bt.c:22:
> In function ‘strncat’,
> inlined from ‘string_set_value’ at util/data-convert-bt.c:274:4:
> /usr/include/powerpc64le-linux-gnu/bits/string_fortified.h:136:10: error:
> ‘__builtin_strncat’ output may be truncated copying 4 bytes from a string of
> length 4 [-Werror=stringop-truncation]
> 136 | return __builtin___strncat_chk (__dest, __src, __len, __bos
> (__dest));
> |
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Signed-off-by: Shawn Landden <sh...@git.icu>
> Cc: Adrian Hunter <adrian.hun...@intel.com>
> Cc: Jiri Olsa <jo...@redhat.com>
> Cc: Namhyung Kim <namhy...@kernel.org>
> Cc: Wang Nan <wangn...@huawei.com>
> LPU-Reference: 20190518183238.10954-1-sh...@git.icu
> Link: https://lkml.kernel.org/n/tip-289f1jice17ta7tr3tstm...@git.kernel.org
> Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
> ---
> tools/perf/util/data-convert-bt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/data-convert-bt.c
> b/tools/perf/util/data-convert-bt.c
> index e0311c9750ad..9097543a818b 100644
> --- a/tools/perf/util/data-convert-bt.c
> +++ b/tools/perf/util/data-convert-bt.c
> @@ -271,7 +271,7 @@ static int string_set_value(struct bt_ctf_field *field,
> const char *string)
> if (i > 0)
> strncpy(buffer, string, i);
> }
> - strncat(buffer + p, numstr, 4);
> + memcpy(buffer + p, numstr, 4);
I took care to have enough context in my patch that you could see what
was going on. I wonder if there is a way to make that care
propate when people add Signed-off-by: lines.
> p += 3;
> }
> }
> --
> 2.20.1
>
