Commit 67072c31 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'tcp-rds-fix-use-after-free-around-kernel-tcp-reqsk' 

Kuniyuki Iwashima says:

====================
tcp/rds: Fix use-after-free around kernel TCP reqsk.

syzkaller reported an warning of netns ref tracker for RDS TCP listener,
which commit 740ea3c4 ("tcp: Clean up kernel listener's reqsk in
inet_twsk_purge()") fixed for per-netns ehash.

This series fixes the bug in the partial fix and fixes the reported bug
in the global ehash.

v4: https://lore.kernel.org/netdev/20240307232151.55963-1-kuniyu@amazon.com/
v3: https://lore.kernel.org/netdev/20240307224423.53315-1-kuniyu@amazon.com/
v2: https://lore.kernel.org/netdev/20240227011041.97375-1-kuniyu@amazon.com/
v1: https://lore.kernel.org/netdev/20240223172448.94084-1-kuniyu@amazon.com/
====================

Link: https://lore.kernel.org/r/20240308200122.64357-1-kuniyu@amazon.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 9187210e 2a750d6a

net/ipv4/inet_timewait_sock.c

+19 −22
Original line number Diff line number Diff line
@@ -263,12 +263,12 @@ void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo, bool rearm) 
}

EXPORT_SYMBOL_GPL(__inet_twsk_schedule);



/* Remove all non full sockets (TIME_WAIT and NEW_SYN_RECV) for dead netns */

void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)

{

	struct inet_timewait_sock *tw;

	struct sock *sk;

	struct hlist_nulls_node *node;

	unsigned int slot;

	struct sock *sk;



	for (slot = 0; slot <= hashinfo->ehash_mask; slot++) {

		struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
@@ -277,38 +277,35 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family) 
		rcu_read_lock();

restart:

		sk_nulls_for_each_rcu(sk, node, &head->chain) {

			if (sk->sk_state != TCP_TIME_WAIT) {

				/* 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);

				}

			int state = inet_sk_state_load(sk);



			if ((1 << state) & ~(TCPF_TIME_WAIT |

					     TCPF_NEW_SYN_RECV))

				continue;

			}



			tw = inet_twsk(sk);

			if ((tw->tw_family != family) ||

				refcount_read(&twsk_net(tw)->ns.count))

			if (sk->sk_family != family ||

			    refcount_read(&sock_net(sk)->ns.count))

				continue;



			if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt)))

			if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))

				continue;



			if (unlikely((tw->tw_family != family) ||

				     refcount_read(&twsk_net(tw)->ns.count))) {

				inet_twsk_put(tw);

			if (unlikely(sk->sk_family != family ||

				     refcount_read(&sock_net(sk)->ns.count))) {

				sock_gen_put(sk);

				goto restart;

			}



			rcu_read_unlock();

			local_bh_disable();

			inet_twsk_deschedule_put(tw);

			if (state == TCP_TIME_WAIT) {

				inet_twsk_deschedule_put(inet_twsk(sk));

			} else {

				struct request_sock *req = inet_reqsk(sk);



				inet_csk_reqsk_queue_drop_and_put(req->rsk_listener,

								  req);

			}

			local_bh_enable();

			goto restart_rcu;

		}

net/ipv4/tcp_minisocks.c

+0 −4
Original line number Diff line number Diff line
@@ -398,10 +398,6 @@ void tcp_twsk_purge(struct list_head *net_exit_list, int family) 
			/* Even if tw_refcount == 1, we must clean up kernel reqsk */

			inet_twsk_purge(net->ipv4.tcp_death_row.hashinfo, family);

		} else if (!purged_once) {

			/* The last refcount is decremented in tcp_sk_exit_batch() */

			if (refcount_read(&net->ipv4.tcp_death_row.tw_refcount) == 1)

				continue;



			inet_twsk_purge(&tcp_hashinfo, family);

			purged_once = true;

		}