diff options
| author | Jiri Olsa <jolsa@kernel.org> | 2024-12-08 15:25:07 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-12-10 10:16:28 -0800 |
| commit | 978c4486cca5c7b9253d3ab98a88c8e769cb9bbd (patch) | |
| tree | dbb6496d5c83d5132757b195c3a3ddfb18391909 /kernel | |
| parent | ef1b808e3b7c98612feceedf985c2fbbeb28f956 (diff) | |
bpf,perf: Fix invalid prog_array access in perf_event_detach_bpf_prog
Syzbot reported [1] crash that happens for following tracing scenario:
- create tracepoint perf event with attr.inherit=1, attach it to the
process and set bpf program to it
- attached process forks -> chid creates inherited event
the new child event shares the parent's bpf program and tp_event
(hence prog_array) which is global for tracepoint
- exit both process and its child -> release both events
- first perf_event_detach_bpf_prog call will release tp_event->prog_array
and second perf_event_detach_bpf_prog will crash, because
tp_event->prog_array is NULL
The fix makes sure the perf_event_detach_bpf_prog checks prog_array
is valid before it tries to remove the bpf program from it.
[1] https://lore.kernel.org/bpf/Z1MR6dCIKajNS6nU@krava/T/#m91dbf0688221ec7a7fc95e896a7ef9ff93b0b8ad
Fixes: 0ee288e69d03 ("bpf,perf: Fix perf_event_detach_bpf_prog error handling")
Reported-by: syzbot+2e0d2840414ce817aaac@syzkaller.appspotmail.com
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241208142507.1207698-1-jolsa@kernel.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a403b05a7091..1b8db5aee9d3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2250,6 +2250,9 @@ void perf_event_detach_bpf_prog(struct perf_event *event) goto unlock; old_array = bpf_event_rcu_dereference(event->tp_event->prog_array); + if (!old_array) + goto put; + ret = bpf_prog_array_copy(old_array, event->prog, NULL, 0, &new_array); if (ret < 0) { bpf_prog_array_delete_safe(old_array, event->prog); @@ -2258,6 +2261,7 @@ void perf_event_detach_bpf_prog(struct perf_event *event) bpf_prog_array_free_sleepable(old_array); } +put: /* * It could be that the bpf_prog is not sleepable (and will be freed * via normal RCU), but is called from a point that supports sleepable |