[PATCH AUTOSEL 4.19 30/49] perf data: Fix 'strncat may truncate' build failure with recent gcc

Sasha Levin
2019-06-08T11:44:04Z

From: Shawn Landden <shawn@git.icu>

[ Upstream commit 97acec7df172cd1e450f81f5e293c0aa145a2797 ]

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 <shawn@git.icu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
LPU-Reference: 20190518183238.10954-1-shawn@git.icu
Link: https://lkml.kernel.org/n/tip-289f1jice17ta7tr3tstm9jm@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 abd38abf1d91..24f2a87cf91d 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);
p += 3;
}
}
--
2.20.1