perf machine: Fix NULL deref in thread__resolve_callchain_sample()

When recording with -j stack, resolve_lbr_callchain_sample() can
dereference a NULL 'chain' pointer while resolving the branch
stack.

$ perf record -j stack -e branches:u uname
perf: Segmentation fault

Fix it by checking 'chain' for NULL before dereferencing it.

Fixes: 29be60c93d2d9300 ("perf build-id: Mark DSO in sample callchains")
Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: Shengming Hu <hu.shengming@zte.com.cn>
Signed-off-by: lvyating <lv.yating@zte.com.cn>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Dai Hualiang <dai.hualiang@zte.com.cn>
Cc: he.yilin@zte.com.cn
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qingtao Liu <liu.qingtao2@zte.com.cn>
Cc: Shen Lin <shen.lin1@zte.com.cn>
Cc: stable@vger.kernel.org
Cc: ye.zhihao1@zte.com.cn
Cc: zhang.cheng35@zte.com.cn
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions