From: Mark Rutland Date: Mon, 6 Jan 2020 12:03:39 +0000 (+0000) Subject: perf: Correctly handle failed perf_get_aux_event() X-Git-Tag: v5.4.14~188 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9d7f2619b02327b1c9f7b574603a993e9a07be66;p=platform%2Fkernel%2Flinux-rpi.git perf: Correctly handle failed perf_get_aux_event() commit da9ec3d3dd0f1240a48920be063448a2242dbd90 upstream. Vince reports a worrying issue: | 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. ... and further the cause: | 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) This seems to be a thinko in commit: ab43762ef010967e ("perf: Allow normal events to output AUX data") ... and we should probably return -EINVAL here, as this should only happen when the new event is mis-configured or does not have a compatible aux_event group leader. Fixes: ab43762ef010967e ("perf: Allow normal events to output AUX data") Reported-by: Vince Weaver Signed-off-by: Mark Rutland Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Alexander Shishkin Tested-by: Vince Weaver Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/events/core.c b/kernel/events/core.c index 8f66a48..6c829e2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11182,8 +11182,10 @@ SYSCALL_DEFINE5(perf_event_open, } } - if (event->attr.aux_output && !perf_get_aux_event(event, group_leader)) + if (event->attr.aux_output && !perf_get_aux_event(event, group_leader)) { + err = -EINVAL; goto err_locked; + } /* * Must be under the same ctx::mutex as perf_install_in_context(),