perf callchain: Fix segfault in thread__resolve_callchain_sample()

Do not dereference 'chain' when it is NULL.

  $ perf record -e intel_pt//u -e branch-misses:u uname
  $ perf report --itrace=l --branch-history
  perf: Segmentation fault

Fixes: e9024d519d89 ("perf callchain: Honour the ordering of PERF_CONTEXT_{USER,KERNEL,etc}")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20191114142538.4097-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7d2e211e376cced5b51fce1cb52f2c90873124c9..71ee078d30f4b5c1fc6dd21d0247ad0be2ca828a 100644 (file)
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2385,7 +2385,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
        }
 
 check_calls:
-       if (callchain_param.order != ORDER_CALLEE) {
+       if (chain && callchain_param.order != ORDER_CALLEE) {
                err = find_prev_cpumode(chain, thread, cursor, parent, root_al,
                                        &cpumode, chain->nr - first_call);
                if (err)