diff options
| author | Masami Hiramatsu (Google) <[email protected]> | 2022-05-28 00:55:39 +0900 |
|---|---|---|
| committer | Steven Rostedt (Google) <[email protected]> | 2022-06-17 17:40:06 -0400 |
| commit | cc72b72073ac982a954d3b43519ca1c28f03c27c (patch) | |
| tree | bb9ee7db0041fb4dee12010424a227c85b866d1c | |
| parent | b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 (diff) | |
tracing/kprobes: Check whether get_kretprobe() returns NULL in kretprobe_dispatcher()
There is a small chance that get_kretprobe(ri) returns NULL in
kretprobe_dispatcher() when another CPU unregisters the kretprobe
right after __kretprobe_trampoline_handler().
To avoid this issue, kretprobe_dispatcher() checks the get_kretprobe()
return value again. And if it is NULL, it returns soon because that
kretprobe is under unregistering process.
This issue has been introduced when the kretprobe is decoupled
from the struct kretprobe_instance by commit d741bf41d7c7
("kprobes: Remove kretprobe hash"). Before that commit, the
struct kretprob_instance::rp directly points the kretprobe
and it is never be NULL.
Link: https://lkml.kernel.org/r/165366693881.797669.16926184644089588731.stgit@devnote2
Reported-by: Yonghong Song <[email protected]>
Fixes: d741bf41d7c7 ("kprobes: Remove kretprobe hash")
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: bpf <[email protected]>
Cc: Kernel Team <[email protected]>
Cc: [email protected]
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
| -rw-r--r-- | kernel/trace/trace_kprobe.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 93507330462c..a245ea673715 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1718,8 +1718,17 @@ static int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs) { struct kretprobe *rp = get_kretprobe(ri); - struct trace_kprobe *tk = container_of(rp, struct trace_kprobe, rp); + struct trace_kprobe *tk; + + /* + * There is a small chance that get_kretprobe(ri) returns NULL when + * the kretprobe is unregister on another CPU between kretprobe's + * trampoline_handler and this function. + */ + if (unlikely(!rp)) + return 0; + tk = container_of(rp, struct trace_kprobe, rp); raw_cpu_inc(*tk->nhit); if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE)) |