Messages in this thread | | | Date | Wed, 17 Jul 2013 11:02:04 +0300 | From | Adrian Hunter <> | Subject | Re: [PATCH V6 06/12] perf tools: remove unnecessary callchain validation |
| |
On 16/07/13 15:05, Jiri Olsa wrote: > On Tue, Jul 16, 2013 at 09:38:12AM +0300, Adrian Hunter wrote: > > SNIP > >> } >> } >> >> -static int perf_session__preprocess_sample(struct perf_session *session, >> - union perf_event *event, struct perf_sample *sample) >> -{ >> - if (event->header.type != PERF_RECORD_SAMPLE || >> - !sample->callchain) >> - return 0; >> - >> - if (!ip_callchain__valid(sample->callchain, event)) { >> - pr_debug("call-chain problem with event, skipping it.\n"); >> - ++session->stats.nr_invalid_chains; >> - session->stats.total_invalid_chains += sample->period; > > How about the '*invalid_chains' stats here? I dont see > it incremented in the parsing routine. > > Also the current behaviour is to increments stats for invalid > callchains, but dont fail. With your changes we fail during the > parsing.
It would fail during parsing sometimes anyway. The code was:
if (type & PERF_SAMPLE_CALLCHAIN) { if (sample_overlap(event, array, sizeof(data->callchain->nr))) return -EFAULT;
data->callchain = (struct ip_callchain *)array;
if (sample_overlap(event, array, data->callchain->nr)) return -EFAULT;
array += 1 + data->callchain->nr; }
But sample overlap did not handle size being effectively negative i.e. 'offset + size' overflows
static bool sample_overlap(const union perf_event *event, const void *offset, u64 size) { const void *base = event;
if (offset + size > base + event->header.size) return true;
return false; }
> > On the other hand.. maybe we should fail ;-) I think that > invalid callchain data is serious enough to be overlooked > by not seeing the nr_invalid_chains got incremented. > > let's see other comments and then silently push it :-) > > jirka > >
| |