linux-kernel - [PATCH AUTOSEL 6.6 21/61] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock

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Message-ID: <20241124134637.3346391-21-sashal@kernel.org>
Date: Sun, 24 Nov 2024 08:44:56 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Ignat Korchagin <ignat@...udflare.com>,
	Kuniyuki Iwashima <kuniyu@...zon.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	marcel@...tmann.org,
	johan.hedberg@...il.com,
	luiz.dentz@...il.com,
	axboe@...nel.dk,
	nathan@...nel.org,
	andrew.shadura@...labora.co.uk,
	linux-bluetooth@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 21/61] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock_alloc()

From: Ignat Korchagin <ignat@...udflare.com>

[ Upstream commit 3945c799f12b8d1f49a3b48369ca494d981ac465 ]

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 <ignat@...udflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Link: https://patch.msgid.link/20241014153808.51894-4-ignat@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 cbff37b327340..c32a2374638b7 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;
 	}
 
-- 
2.43.0