linux-kernel - [tip:perf/core] perf list: Robustify event printing routine

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Message-ID: <tip-57wysblcjfrseb0zg5u7ek10@git.kernel.org>
Date:	Fri, 18 Dec 2015 00:57:55 -0800
From:	tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	jolsa@...hat.com, hpa@...or.com, namhyung@...nel.org,
	tglx@...utronix.de, mingo@...nel.org, dsahern@...il.com,
	linux-kernel@...r.kernel.org, ast@...nel.org,
	adrian.hunter@...el.com, wangnan0@...wei.com, acme@...hat.com
Subject: [tip:perf/core] perf list: Robustify event printing routine

Commit-ID:  fb202539e61b14bc63ac29af10fe5d758ecd880a
Gitweb:     http://git.kernel.org/tip/fb202539e61b14bc63ac29af10fe5d758ecd880a
Author:     Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Fri, 27 Nov 2015 16:04:58 -0300
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Wed, 16 Dec 2015 16:43:10 -0300

perf list: Robustify event printing routine

When a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") added
PERF_COUNT_SW_BPF_OUTPUT we ended up with a new entry in the event_symbols_sw
array that wasn't initialized, thus set to NULL, fix print_symbol_events()
to check for that case so that we don't crash if this happens again.

  (gdb) bt
  #0  __match_glob (ignore_space=false, pat=<optimized out>, str=<optimized out>) at util/string.c:198
  #1  strglobmatch (str=<optimized out>, pat=pat@...ry=0x7fffffffe61d "stall") at util/string.c:252
  #2  0x00000000004993a5 in print_symbol_events (type=1, syms=0x872880 <event_symbols_sw+160>, max=11, name_only=false, event_glob=0x7fffffffe61d "stall")
      at util/parse-events.c:1615
  #3  print_events (event_glob=event_glob@...ry=0x7fffffffe61d "stall", name_only=false) at util/parse-events.c:1675
  #4  0x000000000042c79e in cmd_list (argc=1, argv=0x7fffffffe390, prefix=<optimized out>) at builtin-list.c:68
  #5  0x00000000004788a5 in run_builtin (p=p@...ry=0x871758 <commands+120>, argc=argc@...ry=2, argv=argv@...ry=0x7fffffffe390) at perf.c:370
  #6  0x0000000000420ab0 in handle_internal_command (argv=0x7fffffffe390, argc=2) at perf.c:429
  #7  run_argv (argv=0x7fffffffe110, argcp=0x7fffffffe11c) at perf.c:473
  #8  main (argc=2, argv=0x7fffffffe390) at perf.c:588
  (gdb) p event_symbols_sw[PERF_COUNT_SW_BPF_OUTPUT]
  $4 = {symbol = 0x0, alias = 0x0}
  (gdb)

A patch to robustify perf to not segfault when the next counter gets added in
the kernel will follow this one.

Reported-by: Ingo Molnar <mingo@...nel.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-57wysblcjfrseb0zg5u7ek10@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/parse-events.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 40ae92a..6fc8cd7 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1883,7 +1883,7 @@ restart:
 
 	for (i = 0; i < max; i++, syms++) {
 
-		if (event_glob != NULL &&
+		if (event_glob != NULL && syms->symbol != NULL &&
 		    !(strglobmatch(syms->symbol, event_glob) ||
 		      (syms->alias && strglobmatch(syms->alias, event_glob))))
 			continue;
--
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