linux-kernel - [PATCH AUTOSEL 4.19 06/21] Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock

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Message-ID: <20241124135709.3351371-6-sashal@kernel.org>
Date: Sun, 24 Nov 2024 08:56:39 -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,
	linux-bluetooth@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 06/21] Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock_create()

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

[ Upstream commit 7c4f78cdb8e7501e9f92d291a7d956591bf73be9 ]

bt_sock_alloc() allocates the sk object and attaches it to the provided
sock object. On error l2cap_sock_alloc() frees the sk object, but the
dangling pointer is still attached to the sock object, which may create
use-after-free in other code.

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/20241014153808.51894-3-ignat@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/bluetooth/l2cap_sock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 8dcd3af05d9fc..5a955bd40f7b9 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1659,6 +1659,7 @@ static struct sock *l2cap_sock_alloc(struct net *net, struct socket *sock,
 	chan = l2cap_chan_create();
 	if (!chan) {
 		sk_free(sk);
+		sock->sk = NULL;
 		return NULL;
 	}
 
-- 
2.43.0