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authorDmitry Safonov <dima@arista.com>2021-03-02 05:35:33 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2021-03-06 22:54:25 +0300
commitffc52b7ae5e6ff2b57c05fa8954fd4cae4efaab4 (patch)
tree0cab60c3deccb480125919a1ce2f0f89c9bba3f5 /tools/perf/builtin-diff.c
parent2b1919ec8338fad3e950f264c0c81f8b17eb6c7e (diff)
downloadlinux-ffc52b7ae5e6ff2b57c05fa8954fd4cae4efaab4.tar.xz
perf diff: Don't crash on freeing errno-session on the error path
__cmd_diff() sets result of perf_session__new() to d->session. In case of failure, it's errno and perf-diff may crash with: failed to open perf.data: Permission denied Failed to open perf.data Segmentation fault (core dumped) From the coredump: 0 0x00005569a62b5955 in auxtrace__free (session=0xffffffffffffffff) at util/auxtrace.c:2681 1 0x00005569a626b37d in perf_session__delete (session=0xffffffffffffffff) at util/session.c:295 2 perf_session__delete (session=0xffffffffffffffff) at util/session.c:291 3 0x00005569a618008a in __cmd_diff () at builtin-diff.c:1239 4 cmd_diff (argc=<optimized out>, argv=<optimized out>) at builtin-diff.c:2011 [..] Funny enough, it won't always crash. For me it crashes only if failed file is second in cmd-line: the reason is that cmd_diff() check files for branch-stacks [in check_file_brstack()] and if the first file doesn't have brstacks, it doesn't proceed to try open other files from cmd-line. Check d->session before calling perf_session__delete(). Another solution would be assigning to temporary variable, checking it, but I find it easier to follow with IS_ERR() check in the same function. After some time it's still obvious why the check is needed, and with temp variable it's possible to make the same mistake. Committer testing: $ perf record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ] $ perf diff failed to open perf.data.old: No such file or directory Failed to open perf.data.old $ perf record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ] $ perf diff # Event 'cycles:u' # # Baseline Delta Abs Shared Object Symbol # ........ ......... ................ .......................... # 0.92% +87.66% [unknown] [k] 0xffffffff8825de16 11.39% +0.04% ld-2.32.so [.] __GI___tunables_init 87.70% ld-2.32.so [.] _dl_check_map_versions $ sudo chown root:root perf.data [sudo] password for acme: $ perf diff failed to open perf.data: Permission denied Failed to open perf.data Segmentation fault (core dumped) $ After the patch: $ perf diff failed to open perf.data: Permission denied Failed to open perf.data $ Signed-off-by: Dmitry Safonov <dima@arista.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: dmitry safonov <dima@arista.com> Link: http://lore.kernel.org/lkml/20210302023533.1572231-1-dima@arista.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/builtin-diff.c')
-rw-r--r--tools/perf/builtin-diff.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 8f6c784ce629..878e04b1fab7 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -1236,7 +1236,8 @@ static int __cmd_diff(void)
out_delete:
data__for_each_file(i, d) {
- perf_session__delete(d->session);
+ if (!IS_ERR(d->session))
+ perf_session__delete(d->session);
data__free(d);
}