net: af_can: do not leave a dangling sk pointer in can_create()

jira VULN-41237
cve CVE-2024-56603
commit-author Ignat Korchagin <ignat@cloudflare.com>
commit 811a7ca

On error can_create() frees the allocated sk object, but sock_init_data()
has already attached it to the provided sock object. This will leave a
dangling sk pointer in the sock object and may cause use-after-free later.

	Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
	Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
	Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
	Reviewed-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://patch.msgid.link/20241014153808.51894-5-ignat@cloudflare.com
	Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 811a7ca)
	Signed-off-by: Pratham Patel <ppatel@ciq.com>

Author: thefossguy-ciq

net/can/af_can.c

@@ -200,6 +200,7 @@ static int can_create(struct net *net, struct socket *sock, int protocol,
 		/* release sk on errors */
 		sock_orphan(sk);
 		sock_put(sk);
+		sock->sk = NULL;
 	}
 
  errout: