From: Takashi Iwai tiwai@suse.de
[ Upstream commit 99c23da0eed4fd20cae8243f2b51e10e66aa0951 ]
The sco_send_frame() also takes lock_sock() during memcpy_from_msg() call that may be endlessly blocked by a task with userfaultd technique, and this will result in a hung task watchdog trigger.
Just like the similar fix for hci_sock_sendmsg() in commit 92c685dc5de0 ("Bluetooth: reorganize functions..."), this patch moves the memcpy_from_msg() out of lock_sock() for addressing the hang.
This should be the last piece for fixing CVE-2021-3640 after a few already queued fixes.
Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/bluetooth/sco.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 77f88c7df6053..b3b4ffaa394f6 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -254,7 +254,8 @@ static int sco_connect(struct hci_dev *hdev, struct sock *sk) return err; }
-static int sco_send_frame(struct sock *sk, struct msghdr *msg, int len) +static int sco_send_frame(struct sock *sk, void *buf, int len, + unsigned int msg_flags) { struct sco_conn *conn = sco_pi(sk)->conn; struct sk_buff *skb; @@ -266,15 +267,11 @@ static int sco_send_frame(struct sock *sk, struct msghdr *msg, int len)
BT_DBG("sk %p len %d", sk, len);
- skb = bt_skb_send_alloc(sk, len, msg->msg_flags & MSG_DONTWAIT, &err); + skb = bt_skb_send_alloc(sk, len, msg_flags & MSG_DONTWAIT, &err); if (!skb) return err;
- if (memcpy_from_msg(skb_put(skb, len), msg, len)) { - kfree_skb(skb); - return -EFAULT; - } - + memcpy(skb_put(skb, len), buf, len); hci_send_sco(conn->hcon, skb);
return len; @@ -693,6 +690,7 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) { struct sock *sk = sock->sk; + void *buf; int err;
BT_DBG("sock %p, sk %p", sock, sk); @@ -704,14 +702,24 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg, if (msg->msg_flags & MSG_OOB) return -EOPNOTSUPP;
+ buf = kmalloc(len, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + if (memcpy_from_msg(buf, msg, len)) { + kfree(buf); + return -EFAULT; + } + lock_sock(sk);
if (sk->sk_state == BT_CONNECTED) - err = sco_send_frame(sk, msg, len); + err = sco_send_frame(sk, buf, len, msg->msg_flags); else err = -ENOTCONN;
release_sock(sk); + kfree(buf); return err; }