[tip:perf/core] perf hists browser: Fix segfault if use symbol filter in cmdline

From: tip-bot for Wang Nan
Date: Tue Dec 08 2015 - 00:14:23 EST


Commit-ID: 4938cf0c7a62025bbfbf3db7bcdcc2c33312bedb
Gitweb: http://git.kernel.org/tip/4938cf0c7a62025bbfbf3db7bcdcc2c33312bedb
Author: Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Mon, 7 Dec 2015 02:35:44 +0000
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 7 Dec 2015 12:02:35 -0300

perf hists browser: Fix segfault if use symbol filter in cmdline

If feed perf a symbol filter in cmdline and the result is empty,
pressing 'Enter' in the hist browser causes crash:

# ./perf report perf.data <-- Common mistake for beginners

Then press 'Enter':

perf: Segmentation fault
-------- backtrace --------
/home/wangnan/perf[0x53e578]
/lib64/libc.so.6(+0x3545f)[0x7f76bafe045f]
/home/wangnan/perf[0x539dd4]
/home/wangnan/perf(perf_evlist__tui_browse_hists+0x96)[0x53d216]
/home/wangnan/perf(cmd_report+0x1b9f)[0x442c7f]
/home/wangnan/perf[0x47efa2]
/home/wangnan/perf(main+0x5f5)[0x432fa5]
/lib64/libc.so.6(__libc_start_main+0xf4)[0x7f76bafccbd4]
/home/wangnan/perf[0x4330d4]

This is because 'perf.data' is interpreted as a symbol filter, and the
result is empty, so selection is empty. However,
hist_browser__toggle_fold() forgets to check it.

This patch simply return false when selection is NULL.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1449455746-41952-2-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/ui/browsers/hists.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 84c8251..81def6c3 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -298,6 +298,9 @@ static bool hist_browser__toggle_fold(struct hist_browser *browser)
struct callchain_list *cl = container_of(ms, struct callchain_list, ms);
bool has_children;

+ if (!he || !ms)
+ return false;
+
if (ms == &he->ms)
has_children = hist_entry__toggle_fold(he);
else
--
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