linux-kernel - [PATCH 20/73] perf machine: Null-terminate version char array upon fgets(/proc/version) error

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Date:   Fri, 17 May 2019 16:35:18 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Donald Yandt <donald.yandt@...il.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Avi Kivity <avi@...lladb.com>, Jiri Olsa <jolsa@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Yanmin Zhang <yanmin_zhang@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 20/73] perf machine: Null-terminate version char array upon fgets(/proc/version) error

From: Donald Yandt <donald.yandt@...il.com>

If fgets() fails due to any other error besides end-of-file, the version
char array may not even be null-terminated.

Signed-off-by: Donald Yandt <donald.yandt@...il.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Avi Kivity <avi@...lladb.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Yanmin Zhang <yanmin_zhang@...ux.intel.com>
Fixes: a1645ce12adb ("perf: 'perf kvm' tool for monitoring guest performance from host")
Link: http://lkml.kernel.org/r/20190514110100.22019-1-donald.yandt@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/machine.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 3c520baa198c..28a9541c4835 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1234,8 +1234,9 @@ static char *get_kernel_version(const char *root_dir)
 	if (!file)
 		return NULL;
 
-	version[0] = '\0';
 	tmp = fgets(version, sizeof(version), file);
+	if (!tmp)
+		*version = '\0';
 	fclose(file);
 
 	name = strstr(version, prefix);
-- 
2.20.1