diff options
author | Alexei Starovoitov <ast@plumgrid.com> | 2015-05-15 12:15:21 -0700 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-05-27 08:46:15 +0200 |
commit | dead9f29ddcc69551f35529a252d2704047870d3 (patch) | |
tree | 2f89c58475dd28534155aae9175cd94299bf58e7 /kernel/events/core.c | |
parent | ba155e2d21f6bf05de86a78dbe5bfd8757604a65 (diff) | |
download | op-kernel-dev-dead9f29ddcc69551f35529a252d2704047870d3.zip op-kernel-dev-dead9f29ddcc69551f35529a252d2704047870d3.tar.gz |
perf: Fix race in BPF program unregister
there is a race between perf_event_free_bpf_prog() and free_trace_kprobe():
__free_event()
event->destroy(event)
tp_perf_event_destroy()
perf_trace_destroy()
perf_trace_event_unreg()
which is dropping event->tp_event->perf_refcount and allows to proceed in:
unregister_trace_kprobe()
unregister_kprobe_event()
trace_remove_event_call()
probe_remove_event_call()
free_trace_kprobe()
while __free_event does:
call_rcu(&event->rcu_head, free_event_rcu);
free_event_rcu()
perf_event_free_bpf_prog()
To fix the race simply move perf_event_free_bpf_prog() before
event->destroy(), since event->tp_event is still valid at that point.
Note, perf_trace_destroy() is not racing with trace_remove_event_call()
since they both grab event_mutex.
Reported-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lizefan@huawei.com
Cc: pi3orama@163.com
Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes")
Link: http://lkml.kernel.org/r/1431717321-28772-1-git-send-email-ast@plumgrid.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/core.c')
-rw-r--r-- | kernel/events/core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 1a3bf48..eddf1ed 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3442,7 +3442,6 @@ static void free_event_rcu(struct rcu_head *head) if (event->ns) put_pid_ns(event->ns); perf_event_free_filter(event); - perf_event_free_bpf_prog(event); kfree(event); } @@ -3573,6 +3572,8 @@ static void __free_event(struct perf_event *event) put_callchain_buffers(); } + perf_event_free_bpf_prog(event); + if (event->destroy) event->destroy(event); |