Subject: [PATCH v2 4/8] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock_alloc()

From: Ignat Korchagin <[email-masked]>
Date: Mon, 7 Oct 2024 22:34:58 +0100

bt_sock_alloc() attaches allocated sk object to the provided sock object.
If rfcomm_dlc_alloc() fails, we release the sk object, but leave the
dangling pointer in the sock object, which may cause use-after-free.

Fix this by swapping calls to bt_sock_alloc() and rfcomm_dlc_alloc().

Signed-off-by: Ignat Korchagin <[email-masked]>
---
 net/bluetooth/rfcomm/sock.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 37d63d768afb..0d0c4311da57 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -274,13 +274,13 @@ static struct sock *rfcomm_sock_alloc(struct net *net, struct socket *sock,
 	struct rfcomm_dlc *d;
 	struct sock *sk;
 
-	sk = bt_sock_alloc(net, sock, &rfcomm_proto, proto, prio, kern);
-	if (!sk)
+	d = rfcomm_dlc_alloc(prio);
+	if (!d)
 		return NULL;
 
-	d = rfcomm_dlc_alloc(prio);
-	if (!d) {
-		sk_free(sk);
+	sk = bt_sock_alloc(net, sock, &rfcomm_proto, proto, prio, kern);
+	if (!sk) {
+		rfcomm_dlc_free(d);
 		return NULL;
 	}
 
-- 
2.39.5