Messages in this thread | | | Subject | Re: [PATCH] perf session: check for null pointer before derefernce | From | James Clark <> | Date | Tue, 25 Jan 2022 09:35:49 +0000 |
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On 24/01/2022 20:29, Ameer Hamza wrote: > 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?
Yep looks good. With that change:
Reviewed-by: James Clark <james.clark@arm.com>
> > 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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