Commit 740ea3c4a0b2 ("tcp: Clean up kernel listener's reqsk in
inet_twsk_purge()") added changes in inet_twsk_purge() to purge
reqsk in per-netns ehash during netns dismantle.
inet_csk_reqsk_queue_drop_and_put() will remove reqsk from per-netns
ehash, but the iteration uses sk_nulls_for_each_rcu(), which is not
safe. After removing reqsk, we need to restart iteration.
Also, we need to use refcount_inc_not_zero() to check if reqsk is
freed by its timer.
Fixes: 740ea3c4a0b2 ("tcp: Clean up kernel listener's reqsk in inet_twsk_purge()")
Reported-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
---
net/ipv4/inet_timewait_sock.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 5befa4de5b24..c81f83893fc7 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -278,18 +278,32 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)
restart:
sk_nulls_for_each_rcu(sk, node, &head->chain) {
if (sk->sk_state != TCP_TIME_WAIT) {
+ struct request_sock *req;
+
+ if (likely(sk->sk_state != TCP_NEW_SYN_RECV))
+ continue;
+
/* A kernel listener socket might not hold refcnt for net,
* so reqsk_timer_handler() could be fired after net is
* freed. Userspace listener and reqsk never exist here.
*/
- if (unlikely(sk->sk_state == TCP_NEW_SYN_RECV &&
- hashinfo->pernet)) {
- struct request_sock *req = inet_reqsk(sk);
- inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, req);
+ if (sk->sk_family != family ||
+ refcount_read(&sock_net(sk)->ns.count))
+ continue;
+
+ req = inet_reqsk(sk);
+ if (unlikely(!refcount_inc_not_zero(&req->rsk_refcnt)))
+ continue;
+
+ if (unlikely(sk->sk_family != family ||
+ refcount_read(&sock_net(sk)->ns.count))) {
+ reqsk_put(req);
+ continue;
}
- continue;
+ inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, req);
+ goto restart;
}
tw = inet_twsk(sk);
--
2.30.2
