4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Myungho Jung mhjungk@gmail.com
[ Upstream commit 78abe3d0dfad196959b1246003366e2610775ea6 ]
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: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com Signed-off-by: Myungho Jung mhjungk@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/smc/af_smc.c | 14 ++++++++++++-- net/smc/smc.h | 4 ++++ 2 files changed, 16 insertions(+), 2 deletions(-)
--- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -145,8 +145,14 @@ static int smc_release(struct socket *so 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) @@ -203,6 +209,7 @@ static struct sock *smc_sock_alloc(struc 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; } @@ -818,7 +825,7 @@ static int smc_clcsock_accept(struct 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); @@ -831,7 +838,10 @@ static int smc_clcsock_accept(struct smc } *new_smc = smc_sk(new_sk);
- rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0); + 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; --- a/net/smc/smc.h +++ b/net/smc/smc.h @@ -219,6 +219,10 @@ struct smc_sock { /* smc sock contain * 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)