Commit 2e07e834 authored Dec 09, 2023 by Hyunwoo Kim Committed by Luiz Augusto von Dentz Dec 15, 2023

Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg



This can cause a race with bt_sock_ioctl() because
bt_sock_recvmsg() gets the skb from sk->sk_receive_queue
and then frees it without holding lock_sock.
A use-after-free for a skb occurs with the following flow.
```
bt_sock_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
bt_sock_ioctl() -> skb_peek()
```
Add lock_sock to bt_sock_recvmsg() to fix this issue.

Cc: stable@vger.kernel.org
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

parent 04a342cc

net/bluetooth/af_bluetooth.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -309,11 +309,14 @@ int bt_sock_recvmsg(struct socket sock, struct msghdr msg, size_t len,
		if (flags & MSG_OOB)
		return -EOPNOTSUPP;

		lock_sock(sk);

		skb = skb_recv_datagram(sk, flags, &err);
		if (!skb) {
		if (sk->sk_shutdown & RCV_SHUTDOWN)
		return 0;
		err = 0;

		release_sock(sk);
		return err;
		}

		@@ -343,6 +346,8 @@ int bt_sock_recvmsg(struct socket sock, struct msghdr msg, size_t len,

		skb_free_datagram(sk, skb);

		release_sock(sk);

		if (flags & MSG_TRUNC)
		copied = skblen;