Messages in this thread |  | | From | Alexander Shishkin <> | Subject | Re: [PATCH] perf: correctly handle failed perf_get_aux_event() (was: Re: [perf] perf_event_open() sometimes returning 0) | Date | Tue, 07 Jan 2020 09:39:51 +0200 |
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Mark Rutland <mark.rutland@arm.com> writes:
> On Thu, Jan 02, 2020 at 02:22:47PM -0500, Vince Weaver wrote: >> On Thu, 2 Jan 2020, Vince Weaver wrote: >> >> > so I was tracking down some odd behavior in the perf_fuzzer which turns >> > out to be because perf_even_open() sometimes returns 0 (indicating a file >> > descriptor of 0) even though as far as I can tell stdin is still open. > > Yikes. > >> error is triggered if aux_sample_size has non-zero value. >> >> seems to be this line in kernel/events/core.c: >> >> >> if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) >> goto err_locked; >> >> >> (note, err is never set) > > Looks like that was introduced in commit: > > ab43762ef010967e ("perf: Allow normal events to output AUX data") > > I guess we should return -EINVAL in this case.
That's right. Thanks for looking into this!
> diff --git a/kernel/events/core.c b/kernel/events/core.c > index a1f8bde19b56..2173c23c25b4 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -11465,8 +11465,10 @@ SYSCALL_DEFINE5(perf_event_open, > } > } > > - if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) > + if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) { > + err = -EINVAL; > goto err_locked; > + } >
FWIW, Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Thanks, -- Alex
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