[PATCH] net/sched: act_api: avoid dereferencing ERR_PTR in tcf_idrinfo_destroy

[Shivani Gupta <shivani07g@gmail.com>]

syzbot reported a crash in tc_act_in_hw() during netns teardown where
tcf_idrinfo_destroy() passed an ERR_PTR(-EBUSY) value as a tc_action
pointer, leading to an invalid dereference.

Guard against ERR_PTR entries when iterating the action IDR so teardown
does not call tc_act_in_hw() on an error pointer.

Link: https://syzkaller.appspot.com/bug?extid=8f1c492ffa4644ff3826
Reported-by: syzbot+8f1c492ffa4644ff3826@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8f1c492ffa4644ff3826
Signed-off-by: Shivani Gupta <shivani07g@gmail.com>
---
 net/sched/act_api.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index ff6be5cfe2b0..994f7ffe26a5 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -940,6 +940,10 @@ void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
 	int ret;
 
 	idr_for_each_entry_ul(idr, p, tmp, id) {
+		if (IS_ERR(p)) {
+			WARN_ON_ONCE(1);
+			continue;
+		}
 		if (tc_act_in_hw(p) && !mutex_taken) {
 			rtnl_lock();
 			mutex_taken = true;
-- 
2.34.1