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Bluetooth: sco: Fix lock_sock() blockage by memcpy_from_msg()

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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>
This commit is contained in:
Takashi Iwai 2021-08-28 18:18:18 +02:00 committed by Marcel Holtmann
parent 927ac8da35
commit 99c23da0ee
1 changed files with 16 additions and 8 deletions
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24
net/bluetooth/sco.c
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@ -280,7 +280,8 @@ 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;
@ -292,15 +293,11 @@ 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;
@ -725,6 +722,7 @@ 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);
@ -736,14 +734,24 @@ 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;
}