On Sun, 19 Jun 2022 12:50:27 +0800 Chuang W nashuiliang@gmail.com wrote:
In a scenario where livepatch and aggrprobe coexist on the same function entry, and if this aggrprobe has a post_handler, arm_kprobe() always fails as both livepatch and aggrprobe with post_handler will use FTRACE_OPS_FL_IPMODIFY. Since register_aggr_kprobe() doesn't roll back the post_handler on failed arm_kprobe(), this aggrprobe will no longer be available even if all kprobes on this aggrprobe don't have the post_handler.
Fix to roll back the aggrprobe post_handler for this case. With this patch, if a kprobe that has the post_handler is removed from this aggrprobe (since arm_kprobe() failed), it will be available again.
This looks good to me.
Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org
Thank you!
Fixes: 12310e343755 ("kprobes: Propagate error from arm_kprobe_ftrace()") Signed-off-by: Chuang W nashuiliang@gmail.com Cc: stable@vger.kernel.org
v1 -> v2:
- Add commit details
kernel/kprobes.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index f214f8c088ed..0610b02a3a05 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1300,6 +1300,7 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p) { int ret = 0; struct kprobe *ap = orig_p;
- kprobe_post_handler_t old_post_handler = NULL;
cpus_read_lock(); @@ -1351,6 +1352,9 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p) /* Copy the insn slot of 'p' to 'ap'. */ copy_kprobe(ap, p);
- /* save the old post_handler */
- old_post_handler = ap->post_handler; ret = add_new_kprobe(ap, p);
out: @@ -1365,6 +1369,7 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p) ret = arm_kprobe(ap); if (ret) { ap->flags |= KPROBE_FLAG_DISABLED;
ap->post_handler = old_post_handler; list_del_rcu(&p->list); synchronize_rcu(); }-- 2.34.1