| From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 55/83] perf machine: Guard against NULL in machine__exit() | Date | Fri, 17 Nov 2017 17:15:33 -0300 |
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From: Arnaldo Carvalho de Melo <acme@redhat.com>
A recent fix for 'perf trace' introduced a bug where machine__exit(trace->host) could be called while trace->host was still NULL, so make this more robust by guarding against NULL, just like free() does.
The problem happens, for instance, when !root users try to run 'perf trace':
[acme@jouet linux]$ trace Error: No permissions to read /sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit) Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
perf: Segmentation fault Obtained 7 stack frames. [0x4f1b2e] /lib64/libc.so.6(+0x3671f) [0x7f43a1dd971f] [0x4f3fec] [0x47468b] [0x42a2db] /lib64/libc.so.6(__libc_start_main+0xe9) [0x7f43a1dc3509] [0x42a6c9] Segmentation fault (core dumped) [acme@jouet linux]$
Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andrei Vagin <avagin@openvz.org> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Vasily Averin <vvs@virtuozzo.com> Cc: Wang Nan <wangnan0@huawei.com> Fixes: 33974a414ce2 ("perf trace: Call machine__exit() at exit") Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- tools/perf/util/machine.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 6a8d03c3d9b7..270f3223c6df 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -172,6 +172,9 @@ void machine__exit(struct machine *machine) { int i; + if (machine == NULL) + return; + machine__destroy_kernel_maps(machine); map_groups__exit(&machine->kmaps); dsos__exit(&machine->dsos); -- 2.13.6
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