Em Sun, Apr 28, 2019 at 04:32:27PM +0800, Leo Yan escreveu:
> 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>
> Fixes: 7100b12cf474 ("perf cs-etm: Generate branch sample for exception
> packet")
Thanks, applied both to perf/urgent, testing them now in the containers.
- Arnaldo
> Fixes: 24fff5eb2b93 ("perf cs-etm: Avoid stale branch samples when flush
> packet")
> Signed-off-by: Leo Yan <leo....@linaro.org>
> ---
> 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 110804936fc3..054b480aab04 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);
> --
> 2.17.1
--
- Arnaldo
