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.
Fixes: 12310e343755 ("kprobes: Propagate error from arm_kprobe_ftrace()")
Signed-off-by: Chuang W <nashuiliang@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
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
