From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> conn->sk maybe have been unlinked/freed while waiting for sco_conn_lock so this checks if the conn->sk is still valid by checking if it part of sco_sk_list. Reported-by: syzbot+4c0d0c4cde787116d465@xxxxxxxxxxxxxxxxxxxxxxxxx Tested-by: syzbot+4c0d0c4cde787116d465@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=4c0d0c4cde787116d465 Fixes: ba316be1b6a0 ("Bluetooth: schedule SCO timeouts with delayed_work") Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> --- include/net/bluetooth/bluetooth.h | 1 + net/bluetooth/af_bluetooth.c | 22 ++++++++++++++++++++++ net/bluetooth/sco.c | 18 ++++++++++++------ 3 files changed, 35 insertions(+), 6 deletions(-) diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h index 5d655e109b2c..f66bc85c6411 100644 --- a/include/net/bluetooth/bluetooth.h +++ b/include/net/bluetooth/bluetooth.h @@ -403,6 +403,7 @@ int bt_sock_register(int proto, const struct net_proto_family *ops); void bt_sock_unregister(int proto); void bt_sock_link(struct bt_sock_list *l, struct sock *s); void bt_sock_unlink(struct bt_sock_list *l, struct sock *s); +bool bt_sock_linked(struct bt_sock_list *l, struct sock *s); struct sock *bt_sock_alloc(struct net *net, struct socket *sock, struct proto *prot, int proto, gfp_t prio, int kern); int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index e39fba5565c5..0b4d0a8bd361 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -185,6 +185,28 @@ void bt_sock_unlink(struct bt_sock_list *l, struct sock *sk) } EXPORT_SYMBOL(bt_sock_unlink); +bool bt_sock_linked(struct bt_sock_list *l, struct sock *s) +{ + struct sock *sk; + + if (!l || !s) + return false; + + read_lock(&l->lock); + + sk_for_each(sk, &l->head) { + if (s == sk) { + read_unlock(&l->lock); + return true; + } + } + + read_unlock(&l->lock); + + return false; +} +EXPORT_SYMBOL(bt_sock_linked); + void bt_accept_enqueue(struct sock *parent, struct sock *sk, bool bh) { const struct cred *old_cred; diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index a5ac160c592e..1c7252a36866 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -76,6 +76,16 @@ struct sco_pinfo { #define SCO_CONN_TIMEOUT (HZ * 40) #define SCO_DISCONN_TIMEOUT (HZ * 2) +static struct sock *sco_sock_hold(struct sco_conn *conn) +{ + if (!conn || !bt_sock_linked(&sco_sk_list, conn->sk)) + return NULL; + + sock_hold(conn->sk); + + return conn->sk; +} + static void sco_sock_timeout(struct work_struct *work) { struct sco_conn *conn = container_of(work, struct sco_conn, @@ -87,9 +97,7 @@ static void sco_sock_timeout(struct work_struct *work) sco_conn_unlock(conn); return; } - sk = conn->sk; - if (sk) - sock_hold(sk); + sk = sco_sock_hold(conn); sco_conn_unlock(conn); if (!sk) @@ -194,9 +202,7 @@ static void sco_conn_del(struct hci_conn *hcon, int err) /* Kill socket */ sco_conn_lock(conn); - sk = conn->sk; - if (sk) - sock_hold(sk); + sk = sco_sock_hold(conn); sco_conn_unlock(conn); if (sk) { -- 2.47.0
