From: Leo Yan <leo....@linaro.org> Robert Walker reported a segmentation fault is observed when process CoreSight trace data; this issue can be easily reproduced by the command 'perf report --itrace=i1000i' for decoding tracing data.
If neither the 'b' flag (synthesize branches events) nor 'l' flag (synthesize last branch entries) are specified to option '--itrace', cs_etm_queue::prev_packet will not been initialised. After merging the code to support exception packets and sample flags, there introduced a number of uses of cs_etm_queue::prev_packet without checking whether it is valid, for these cases any accessing to uninitialised prev_packet will cause crash. As cs_etm_queue::prev_packet is used more widely now and it's already hard to follow which functions have been called in a context where the validity of cs_etm_queue::prev_packet has been checked, this patch always allocates memory for cs_etm_queue::prev_packet. Reported-by: Robert Walker <robert.wal...@arm.com> Suggested-by: Robert Walker <robert.wal...@arm.com> Signed-off-by: Leo Yan <leo....@linaro.org> Tested-by: Robert Walker <robert.wal...@arm.com> Cc: Alexander Shishkin <alexander.shish...@linux.intel.com> Cc: Jiri Olsa <jo...@redhat.com> Cc: Mathieu Poirier <mathieu.poir...@linaro.org> Cc: Mike Leach <mike.le...@linaro.org> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Suzuki K Poulouse <suzuki.poul...@arm.com> Cc: linux-arm-ker...@lists.infradead.org Fixes: 7100b12cf474 ("perf cs-etm: Generate branch sample for exception packet") Fixes: 24fff5eb2b93 ("perf cs-etm: Avoid stale branch samples when flush packet") Link: http://lkml.kernel.org/r/20190428083228.20246-1-leo....@linaro.org Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/util/cs-etm.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 7777cfc1ad8c..de488b43f440 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -422,11 +422,9 @@ static struct cs_etm_queue *cs_etm__alloc_queue(struct cs_etm_auxtrace *etm) if (!etmq->packet) goto out_free; - if (etm->synth_opts.last_branch || etm->sample_branches) { - etmq->prev_packet = zalloc(szp); - if (!etmq->prev_packet) - goto out_free; - } + etmq->prev_packet = zalloc(szp); + if (!etmq->prev_packet) + goto out_free; if (etm->synth_opts.last_branch) { size_t sz = sizeof(struct branch_stack); -- 2.20.1