Messages in this thread Patch in this message | | | Date | Tue, 25 Jan 2022 01:29:07 +0500 | From | Ameer Hamza <> | Subject | Re: [PATCH] perf session: check for null pointer before derefernce |
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On Mon, Jan 24, 2022 at 03:30:17PM +0000, James Clark wrote: > > > On 24/01/2022 15:00, Ameer Hamza wrote: > > Move null pointer check before dereferncing the variable > > > > Addresses-Coverity: 1497622 ("Derereference before null check") > > > > Signed-off-by: Ameer Hamza <amhamza.mgc@gmail.com> > > --- > > tools/perf/util/session.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > > index f19348dddd55..e1014ab62c10 100644 > > --- a/tools/perf/util/session.c > > +++ b/tools/perf/util/session.c > > @@ -1503,11 +1503,11 @@ static int machines__deliver_event(struct machines *machines, > > ++evlist->stats.nr_unknown_id; > > return 0; > > } > > - dump_sample(evsel, event, sample, perf_env__arch(machine->env)); > > if (machine == NULL) { > > ++evlist->stats.nr_unprocessable_samples; > > return 0; > > } > > + dump_sample(evsel, event, sample, perf_env__arch(machine->env)); > > return evlist__deliver_sample(evlist, tool, event, sample, evsel, machine); > > case PERF_RECORD_MMAP: > > return tool->mmap(tool, event, sample, machine); > > > > Hi Ameer, > > This mistake was made recently, but I don't think your change is the desired behavior. > > It should be possible to dump stuff if machine is null. null or an empty string > should be passed to dump_sample(). It looks like some of the printfs still attempt to > show something in this case, although I didn't check them all.
Hi James,
Thank you for your response. I understand your point.
Do you think following changes would be ok?
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index f19348dddd55..210eeee3dd70 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1503,11 +1503,12 @@ static int machines__deliver_event(struct machines *machines, ++evlist->stats.nr_unknown_id; return 0; } - dump_sample(evsel, event, sample, perf_env__arch(machine->env)); if (machine == NULL) { ++evlist->stats.nr_unprocessable_samples; + dump_sample(evsel, event, sample, perf_env__arch(NULL)); return 0; } + dump_sample(evsel, event, sample, perf_env__arch(machine->env)); return evlist__deliver_sample(evlist, tool, event, sample, evsel, machine); case PERF_RECORD_MMAP: return tool->mmap(tool, event, sample, machine); Thanks, Hamza
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