The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 2bef101686951c743a6c98ca68cc3b3193f1fb81
Gitweb: https://git.kernel.org/tip/2bef101686951c743a6c98ca68cc3b3193f1fb81
Author: Mark Rutland <mark.rutland@xxxxxxx>
AuthorDate: Mon, 06 Jan 2020 12:03:39
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 17 Jan 2020 10:19:24 +01:00
perf: Correctly handle failed perf_get_aux_event()
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 <vincent.weaver@xxxxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Acked-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Tested-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
---
kernel/events/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index a1f8bde..2173c23 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;
+ }
/*
* Must be under the same ctx::mutex as perf_install_in_context(),
|