From 406996f36e01b5da0685e8e205302448b29feba3 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Tue, 13 Mar 2018 12:01:43 -0700 Subject: [PATCH] kcm: lock lower socket in kcm_attach [ Upstream commit 2cc683e88c0c993ac3721d9b702cb0630abe2879 ] Need to lock lower socket in order to provide mutual exclusion with kcm_unattach. v2: Add Reported-by for syzbot Fixes: ab7ac4eb9832e32a09f4e804 ("kcm: Kernel Connection Multiplexor module") Reported-by: syzbot+ea75c0ffcd353d32515f064aaebefc5279e6161e@syzkaller.appspotmail.com Signed-off-by: Tom Herbert Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/kcm/kcmsock.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 179cd9b..63e6d08 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -1375,24 +1375,32 @@ static int kcm_attach(struct socket *sock, struct socket *csock, struct list_head *head; int index = 0; struct strp_callbacks cb; - int err; + int err = 0; csk = csock->sk; if (!csk) return -EINVAL; + lock_sock(csk); + /* Only allow TCP sockets to be attached for now */ if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) || - csk->sk_protocol != IPPROTO_TCP) - return -EOPNOTSUPP; + csk->sk_protocol != IPPROTO_TCP) { + err = -EOPNOTSUPP; + goto out; + } /* Don't allow listeners or closed sockets */ - if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) - return -EOPNOTSUPP; + if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) { + err = -EOPNOTSUPP; + goto out; + } psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL); - if (!psock) - return -ENOMEM; + if (!psock) { + err = -ENOMEM; + goto out; + } psock->mux = mux; psock->sk = csk; @@ -1406,7 +1414,7 @@ static int kcm_attach(struct socket *sock, struct socket *csock, err = strp_init(&psock->strp, csk, &cb); if (err) { kmem_cache_free(kcm_psockp, psock); - return err; + goto out; } write_lock_bh(&csk->sk_callback_lock); @@ -1418,7 +1426,8 @@ static int kcm_attach(struct socket *sock, struct socket *csock, write_unlock_bh(&csk->sk_callback_lock); strp_done(&psock->strp); kmem_cache_free(kcm_psockp, psock); - return -EALREADY; + err = -EALREADY; + goto out; } psock->save_data_ready = csk->sk_data_ready; @@ -1454,7 +1463,10 @@ static int kcm_attach(struct socket *sock, struct socket *csock, /* Schedule RX work in case there are already bytes queued */ strp_check_rcv(&psock->strp); - return 0; +out: + release_sock(csk); + + return err; } static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info) @@ -1506,6 +1518,7 @@ static void kcm_unattach(struct kcm_psock *psock) if (WARN_ON(psock->rx_kcm)) { write_unlock_bh(&csk->sk_callback_lock); + release_sock(csk); return; } -- 2.7.4