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Subject[PATCH AUTOSEL 4.19 042/158] perf jvmti: Address gcc string overflow warning for strncpy()
Date
From: Jiri Olsa <jolsa@redhat.com>

[ Upstream commit 279ab04dbea1370d2eac0f854270369ccaef8a44 ]

We are getting false positive gcc warning when we compile with gcc9 (9.1.1):

CC jvmti/libjvmti.o
In file included from /usr/include/string.h:494,
from jvmti/libjvmti.c:5:
In function ‘strncpy’,
inlined from ‘copy_class_filename.constprop’ at jvmti/libjvmti.c:166:3:
/usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound depends on the length of the source argument [-Werror=stringop-overflow=]
106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
jvmti/libjvmti.c: In function ‘copy_class_filename.constprop’:
jvmti/libjvmti.c:165:26: note: length computed here
165 | size_t file_name_len = strlen(file_name);
| ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

As per Arnaldo's suggestion use strlcpy(), which does the same thing and keeps
gcc silent.

Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ben Gainey <ben.gainey@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20190531131321.GB1281@krava
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/jvmti/libjvmti.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
index 6add3e982614..3361d98a4edd 100644
--- a/tools/perf/jvmti/libjvmti.c
+++ b/tools/perf/jvmti/libjvmti.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
+#include <linux/string.h>
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
@@ -150,8 +151,7 @@ copy_class_filename(const char * class_sign, const char * file_name, char * resu
result[i] = '\0';
} else {
/* fallback case */
- size_t file_name_len = strlen(file_name);
- strncpy(result, file_name, file_name_len < max_length ? file_name_len : max_length);
+ strlcpy(result, file_name, max_length);
}
}

--
2.20.1
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