perf trace: Fix read_string()

We did not account for the enclosing \0. Depending on what malloc()
gave us this resulted in corrupted version string printouts.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 1 deletions

diff --git a/tools/perf/util/trace-event-read.c b/tools/perf/util/trace-event-read.c
index b12e4903739a..a1217a10632f 100644
--- a/tools/perf/util/trace-event-read.c
+++ b/tools/perf/util/trace-event-read.c
@@ -113,8 +113,11 @@ static char *read_string(void)
                 }
         }
 
+        /* trailing \0: */
+        i++;
+
         /* move the file descriptor to the end of the string */
-        r = lseek(input_fd, -(r - (i+1)), SEEK_CUR);
+        r = lseek(input_fd, -(r - i), SEEK_CUR);
         if (r < 0)
                 die("lseek");