net: unix: allow set_peek_off to fail

[ Upstream commit 12663bfc97c8b3fdb292428105dd92d563164050 ]

unix_dgram_recvmsg() will hold the readlock of the socket until recv
is complete.

In the same time, we may try to setsockopt(SO_PEEK_OFF) which will hang until
unix_dgram_recvmsg() will complete (which can take a while) without allowing
us to break out of it, triggering a hung task spew.

Instead, allow set_peek_off to fail, this way userspace will not hang.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/net.h b/include/linux/net.h
index 0c4ae5d..65545ac 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -180,7 +180,7 @@ struct proto_ops {
                                      int offset, size_t size, int flags);
        ssize_t         (*splice_read)(struct socket *sock,  loff_t *ppos,
                                       struct pipe_inode_info *pipe, size_t len, unsigned int flags);
-       void            (*set_peek_off)(struct sock *sk, int val);
+       int             (*set_peek_off)(struct sock *sk, int val);
 };
 
 #define DECLARE_SOCKADDR(type, dst, src)       \

diff --git a/net/core/sock.c b/net/core/sock.c
index 6565431..50a345e 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -885,7 +885,7 @@ set_rcvbuf:
 
        case SO_PEEK_OFF:
                if (sock->ops->set_peek_off)
-                       sock->ops->set_peek_off(sk, val);
+                       ret = sock->ops->set_peek_off(sk, val);
                else
                        ret = -EOPNOTSUPP;
                break;

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 8664ad0..2ee993c 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -529,13 +529,17 @@ static int unix_seqpacket_sendmsg(struct kiocb *, struct socket *,
 static int unix_seqpacket_recvmsg(struct kiocb *, struct socket *,
                                  struct msghdr *, size_t, int);
 
-static void unix_set_peek_off(struct sock *sk, int val)
+static int unix_set_peek_off(struct sock *sk, int val)
 {
        struct unix_sock *u = unix_sk(sk);
 
-       mutex_lock(&u->readlock);
+       if (mutex_lock_interruptible(&u->readlock))
+               return -EINTR;
+
        sk->sk_peek_off = val;
        mutex_unlock(&u->readlock);
+
+       return 0;
 }