diff options
| author | Allison Henderson <achender@kernel.org> | 2026-02-16 15:26:43 -0700 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-02-19 15:57:56 +0100 |
| commit | 6bf45704a92a128a8bfb2dd4d550c61b257c8f9a (patch) | |
| tree | c566dd75887c6a9424173091d4ca0806b268a73f | |
| parent | 45be47bf5d7db0f762a93e9c0ede6cb3c91edf3b (diff) | |
net/rds: Fix NULL pointer dereference in rds_tcp_accept_one
Save a local pointer to new_sock->sk and hold a reference before
installing callbacks in rds_tcp_accept_one. After
rds_tcp_set_callbacks() or rds_tcp_reset_callbacks(), tc->t_sock is
set to new_sock which may race with the shutdown path. A concurrent
rds_tcp_conn_path_shutdown() may call sock_release(), which sets
new_sock->sk = NULL and may eventually free sk when the refcount
reaches zero.
Subsequent accesses to new_sock->sk->sk_state would dereference NULL,
causing the crash. The fix saves a local sk pointer before callbacks
are installed so that sk_state can be accessed safely even after
new_sock->sk is nulled, and uses sock_hold()/sock_put() to ensure
sk itself remains valid for the duration.
Fixes: 826c1004d4ae ("net/rds: rds_tcp_conn_path_shutdown must not discard messages")
Reported-by: syzbot+96046021045ffe6d7709@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=96046021045ffe6d7709
Signed-off-by: Allison Henderson <achender@kernel.org>
Link: https://patch.msgid.link/20260216222643.2391390-1-achender@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | net/rds/tcp_listen.c | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c index 6fb5c928b8fd..b4ab68a1da6d 100644 --- a/net/rds/tcp_listen.c +++ b/net/rds/tcp_listen.c @@ -177,6 +177,7 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn) struct rds_tcp_connection *rs_tcp = NULL; int conn_state; struct rds_conn_path *cp; + struct sock *sk; struct in6_addr *my_addr, *peer_addr; #if !IS_ENABLED(CONFIG_IPV6) struct in6_addr saddr, daddr; @@ -298,6 +299,17 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn) rds_conn_path_drop(cp, 0); goto rst_nsk; } + /* Save a local pointer to sk and hold a reference before setting + * callbacks. Once callbacks are set, a concurrent + * rds_tcp_conn_path_shutdown() may call sock_release(), which + * sets new_sock->sk to NULL and drops a reference on sk. + * The local pointer lets us safely access sk_state below even + * if new_sock->sk has been nulled, and sock_hold() keeps sk + * itself valid until we are done. + */ + sk = new_sock->sk; + sock_hold(sk); + if (rs_tcp->t_sock) { /* Duelling SYN has been handled in rds_tcp_accept_one() */ rds_tcp_reset_callbacks(new_sock, cp); @@ -316,13 +328,15 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn) * knowing that "rds_tcp_conn_path_shutdown" will * dequeue pending messages. */ - if (new_sock->sk->sk_state == TCP_CLOSE_WAIT || - new_sock->sk->sk_state == TCP_LAST_ACK || - new_sock->sk->sk_state == TCP_CLOSE) + if (READ_ONCE(sk->sk_state) == TCP_CLOSE_WAIT || + READ_ONCE(sk->sk_state) == TCP_LAST_ACK || + READ_ONCE(sk->sk_state) == TCP_CLOSE) rds_conn_path_drop(cp, 0); else queue_delayed_work(cp->cp_wq, &cp->cp_recv_w, 0); + sock_put(sk); + new_sock = NULL; ret = 0; if (conn->c_npaths == 0) |