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authorMasami Hiramatsu (Google) <mhiramat@kernel.org>2022-05-28 00:55:39 +0900
committerSteven Rostedt (Google) <rostedt@goodmis.org>2022-06-17 17:40:06 -0400
commitcc72b72073ac982a954d3b43519ca1c28f03c27c (patch)
treebb9ee7db0041fb4dee12010424a227c85b866d1c /kernel
parentb13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 (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 <yhs@fb.com> Fixes: d741bf41d7c7 ("kprobes: Remove kretprobe hash") Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: bpf <bpf@vger.kernel.org> Cc: Kernel Team <kernel-team@fb.com> Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace_kprobe.c11
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))