Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.4 09/27] net: unix: allow set_peek_off to fail | Date | Mon, 13 Jan 2014 16:26:23 -0800 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Sasha Levin <sasha.levin@oracle.com>
[ 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> --- include/linux/net.h | 2 +- net/core/sock.c | 2 +- net/unix/af_unix.c | 8 ++++++-- 3 files changed, 8 insertions(+), 4 deletions(-)
--- a/include/linux/net.h +++ b/include/linux/net.h @@ -215,7 +215,7 @@ 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) \ --- a/net/core/sock.c +++ b/net/core/sock.c @@ -795,7 +795,7 @@ 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; --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -524,13 +524,17 @@ static int unix_seqpacket_sendmsg(struct 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; }
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