From: Arnaldo Carvalho de Melo acme@redhat.com

commit 4a2233b194c77ae1ea8304cb7c00b551de4313f0 upstream.

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 Signed-off-by: Tommi Rantala tommi.t.rantala@nokia.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 968fd0454e6b..d246080cd85e 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -156,6 +156,9 @@ void machine__delete_threads(struct machine *machine)

void machine__exit(struct machine *machine) { + if (machine == NULL) + return; + machine__destroy_kernel_maps(machine); map_groups__exit(&machine->kmaps); dsos__exit(&machine->dsos);