Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock_create()

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@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241014153808.51894-3-ignat@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index ba437c6f6ee591a5624f5fbfbf28f2a80d399372..18e89e764f3b4232b73dac3ca44e7c7192051688 100644 (file)
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1886,6 +1886,7 @@ 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;
        }