diff options
authorYonghong Song <yhs@fb.com>2017-09-18 16:38:36 -0700
committerDavid S. Miller <davem@davemloft.net>2017-09-20 14:10:29 -0700
commitec9dd352d591f0c90402ec67a317c1ed4fb2e638 (patch)
parent008ba2a13f2d04c947adc536d19debb8fe66f110 (diff)
bpf: one perf event close won't free bpf program attached by another perf event
This patch fixes a bug exhibited by the following scenario: 1. fd1 = perf_event_open with attr.config = ID1 2. attach bpf program prog1 to fd1 3. fd2 = perf_event_open with attr.config = ID1 <this will be successful> 4. user program closes fd2 and prog1 is detached from the tracepoint. 5. user program with fd1 does not work properly as tracepoint no output any more. The issue happens at step 4. Multiple perf_event_open can be called successfully, but only one bpf prog pointer in the tp_event. In the current logic, any fd release for the same tp_event will free the tp_event->prog. The fix is to free tp_event->prog only when the closing fd corresponds to the one which registered the program. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 7f11050746ae..2e0f22298fe9 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -272,6 +272,7 @@ struct trace_event_call {
int perf_refcount;
struct hlist_head __percpu *perf_events;
struct bpf_prog *prog;
+ struct perf_event *bpf_prog_owner;
int (*perf_perm)(struct trace_event_call *,
struct perf_event *);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3e691b75b2db..6bc21e202ae4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8171,6 +8171,7 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
event->tp_event->prog = prog;
+ event->tp_event->bpf_prog_owner = event;
return 0;
@@ -8185,7 +8186,7 @@ static void perf_event_free_bpf_prog(struct perf_event *event)
prog = event->tp_event->prog;
- if (prog) {
+ if (prog && event->tp_event->bpf_prog_owner == event) {
event->tp_event->prog = NULL;