3.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sasha Levin <sasha.le...@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.le...@oracle.com>
Acked-by: Pavel Emelyanov <xe...@parallels.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@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
@@ -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) \
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -888,7 +888,7 @@ 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
@@ -530,13 +530,17 @@ 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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