[PATCH 1/2] Bluetooth: ISO: fix UAF in iso_recv_frame

[Muhammad Bilal <meatuni001@gmail.com>]

iso_recv_frame reads conn->sk under iso_conn_lock but releases the lock
before using sk, with no reference held. A concurrent iso_sock_kill()
can free sk in that window, causing use-after-free on sk->sk_state and
sock_queue_rcv_skb().

Fix by replacing the bare pointer read with iso_sock_hold(conn), which
calls sock_hold() while the spinlock is held, atomically elevating the
refcount before the lock drops. Add a drop_put label so sock_put() is
called on all exit paths where the hold succeeded.

Fixes: ccf74f2390d60a2f9a75ef496d2564abb478f46a ("Bluetooth: Add BTPROTO_ISO socket type")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
---
 net/bluetooth/iso.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index d7af617cda45..f03b7fa5dccc 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -564,7 +564,7 @@ static void iso_recv_frame(struct iso_conn *conn, struct sk_buff *skb)
 	struct sock *sk;
 
 	iso_conn_lock(conn);
-	sk = conn->sk;
+	sk = iso_sock_hold(conn);
 	iso_conn_unlock(conn);
 
 	if (!sk)
@@ -573,11 +573,15 @@ static void iso_recv_frame(struct iso_conn *conn, struct sk_buff *skb)
 	BT_DBG("sk %p len %d", sk, skb->len);
 
 	if (sk->sk_state != BT_CONNECTED)
-		goto drop;
+		goto drop_put;
 
-	if (!sock_queue_rcv_skb(sk, skb))
+	if (!sock_queue_rcv_skb(sk, skb)) {
+		sock_put(sk);
 		return;
+	}
 
+drop_put:
+	sock_put(sk);
 drop:
 	kfree_skb(skb);
 }
-- 
2.53.0