Commit 78abe3d0 authored by Myungho Jung's avatar Myungho Jung Committed by David S. Miller
Browse files

net/smc: fix TCP fallback socket release 



clcsock can be released while kernel_accept() references it in TCP
listen worker. Also, clcsock needs to wake up before released if TCP
fallback is used and the clcsock is blocked by accept. Add a lock to
safely release clcsock and call kernel_sock_shutdown() to wake up
clcsock from accept in smc_release().

Reported-by: default avatar <syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+e3132895630f957306bc@syzkaller.appspotmail.com>
Signed-off-by: default avatarMyungho Jung <mhjungk@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f7db2beb

net/smc/af_smc.c

+12 −2
Original line number Diff line number Diff line
@@ -147,8 +147,14 @@ static int smc_release(struct socket *sock) 
		sk->sk_shutdown |= SHUTDOWN_MASK;

	}

	if (smc->clcsock) {

		if (smc->use_fallback && sk->sk_state == SMC_LISTEN) {

			/* wake up clcsock accept */

			rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);

		}

		mutex_lock(&smc->clcsock_release_lock);

		sock_release(smc->clcsock);

		smc->clcsock = NULL;

		mutex_unlock(&smc->clcsock_release_lock);

	}

	if (smc->use_fallback) {

		if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
@@ -205,6 +211,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock, 
	spin_lock_init(&smc->conn.send_lock);

	sk->sk_prot->hash(sk);

	sk_refcnt_debug_inc(sk);

	mutex_init(&smc->clcsock_release_lock);



	return sk;

}
@@ -821,7 +828,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc) 
	struct socket *new_clcsock = NULL;

	struct sock *lsk = &lsmc->sk;

	struct sock *new_sk;

	int rc;

	int rc = -EINVAL;



	release_sock(lsk);

	new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol);
@@ -834,7 +841,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc) 
	}

	*new_smc = smc_sk(new_sk);



	mutex_lock(&lsmc->clcsock_release_lock);

	if (lsmc->clcsock)

		rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);

	mutex_unlock(&lsmc->clcsock_release_lock);

	lock_sock(lsk);

	if  (rc < 0)

		lsk->sk_err = -rc;

net/smc/smc.h

+4 −0
Original line number Diff line number Diff line
@@ -219,6 +219,10 @@ struct smc_sock { /* smc sock container */ 
						 * started, waiting for unsent

						 * data to be sent

						 */

	struct mutex            clcsock_release_lock;

						/* protects clcsock of a listen

						 * socket

						 * */

};



static inline struct smc_sock *smc_sk(const struct sock *sk)

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