Re: [syzbot] [net?] possible deadlock in gtp_encap_enable_socket

[Hillf Danton <hdanton@sina.com>]

On Mon, 23 Sep 2024 08:46:24 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    9410645520e9 Merge tag 'net-next-6.12' of git://git.kernel..
> git tree:       net-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=110c6c27980000

#syz test

--- x/net/smc/af_smc.c
+++ y/net/smc/af_smc.c
@@ -3053,9 +3053,7 @@ int smc_setsockopt(struct socket *sock,
 	/* generic setsockopts reaching us here always apply to the
 	 * CLC socket
 	 */
-	mutex_lock(&smc->clcsock_release_lock);
 	if (!smc->clcsock) {
-		mutex_unlock(&smc->clcsock_release_lock);
 		return -EBADF;
 	}
 	if (unlikely(!smc->clcsock->ops->setsockopt))
@@ -3067,7 +3065,6 @@ int smc_setsockopt(struct socket *sock,
 		sk->sk_err = smc->clcsock->sk->sk_err;
 		sk_error_report(sk);
 	}
-	mutex_unlock(&smc->clcsock_release_lock);
 
 	if (optlen < sizeof(int))
 		return -EINVAL;
@@ -3133,19 +3130,15 @@ int smc_getsockopt(struct socket *sock,
 		return __smc_getsockopt(sock, level, optname, optval, optlen);
 
 	smc = smc_sk(sock->sk);
-	mutex_lock(&smc->clcsock_release_lock);
 	if (!smc->clcsock) {
-		mutex_unlock(&smc->clcsock_release_lock);
 		return -EBADF;
 	}
 	/* socket options apply to the CLC socket */
 	if (unlikely(!smc->clcsock->ops->getsockopt)) {
-		mutex_unlock(&smc->clcsock_release_lock);
 		return -EOPNOTSUPP;
 	}
 	rc = smc->clcsock->ops->getsockopt(smc->clcsock, level, optname,
 					   optval, optlen);
-	mutex_unlock(&smc->clcsock_release_lock);
 	return rc;
 }
 
--