[PATCH 14/24] perf probe: Fix possible double free on error

From: Arnaldo Carvalho de Melo
Date: Thu Mar 12 2015 - 17:32:28 EST

From: He Kuang <hekuang@xxxxxxxxxx>

A double free occurred when get source file path failed. If lr->path
failed to assign a new value, it will be freed as the old path and then
be freed again during line_range__clear(), and causes this:

$ perf probe -L do_execve -k vmlinux
*** Error in `/usr/bin/perf': double free or corruption (fasttop):
0x0000000000a9ac50 ***
======= Backtrace: =========

This patch fix this problem.

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1425463302-1687-1-git-send-email-hekuang@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
tools/perf/util/probe-event.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 8af8e7f55254..e2bf620f98cb 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -790,7 +790,11 @@ static int __show_line_range(struct line_range *lr, const char *module,
/* Convert source file path */
tmp = lr->path;
ret = get_real_path(tmp, lr->comp_dir, &lr->path);
- free(tmp); /* Free old path */
+ /* Free old path when new path is assigned */
+ if (tmp != lr->path)
+ free(tmp);
if (ret < 0) {
pr_warning("Failed to find source file path.\n");
return ret;

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