releases/3.4.77/net-unix-allow-set_peek_off-to-fail.patch

   1 From foo@baz Mon Jan 13 09:28:30 PST 2014
   2 From: Sasha Levin <sasha.levin@oracle.com>
   3 Date: Sat, 7 Dec 2013 17:26:27 -0500
   4 Subject: net: unix: allow set_peek_off to fail
   5
   6 From: Sasha Levin <sasha.levin@oracle.com>
   7
   8 [ Upstream commit 12663bfc97c8b3fdb292428105dd92d563164050 ]
   9
  10 unix_dgram_recvmsg() will hold the readlock of the socket until recv
  11 is complete.
  12
  13 In the same time, we may try to setsockopt(SO_PEEK_OFF) which will hang until
  14 unix_dgram_recvmsg() will complete (which can take a while) without allowing
  15 us to break out of it, triggering a hung task spew.
  16
  17 Instead, allow set_peek_off to fail, this way userspace will not hang.
  18
  19 Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
  20 Acked-by: Pavel Emelyanov <xemul@parallels.com>
  21 Signed-off-by: David S. Miller <davem@davemloft.net>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  23 ---
  24  include/linux/net.h |    2 +-
  25  net/core/sock.c     |    2 +-
  26  net/unix/af_unix.c  |    8 ++++++--
  27  3 files changed, 8 insertions(+), 4 deletions(-)
  28
  29 --- a/include/linux/net.h
  30 +++ b/include/linux/net.h
  31 @@ -215,7 +215,7 @@ struct proto_ops {
  32                                       int offset, size_t size, int flags);
  33         ssize_t         (*splice_read)(struct socket *sock,  loff_t *ppos,
  34                                        struct pipe_inode_info *pipe, size_t len, unsigned int flags);
  35 -       void            (*set_peek_off)(struct sock *sk, int val);
  36 +       int             (*set_peek_off)(struct sock *sk, int val);
  37  };
  38
  39  #define DECLARE_SOCKADDR(type, dst, src)       \
  40 --- a/net/core/sock.c
  41 +++ b/net/core/sock.c
  42 @@ -795,7 +795,7 @@ set_rcvbuf:
  43
  44         case SO_PEEK_OFF:
  45                 if (sock->ops->set_peek_off)
  46 -                       sock->ops->set_peek_off(sk, val);
  47 +                       ret = sock->ops->set_peek_off(sk, val);
  48                 else
  49                         ret = -EOPNOTSUPP;
  50                 break;
  51 --- a/net/unix/af_unix.c
  52 +++ b/net/unix/af_unix.c
  53 @@ -524,13 +524,17 @@ static int unix_seqpacket_sendmsg(struct
  54  static int unix_seqpacket_recvmsg(struct kiocb *, struct socket *,
  55                                   struct msghdr *, size_t, int);
  56
  57 -static void unix_set_peek_off(struct sock *sk, int val)
  58 +static int unix_set_peek_off(struct sock *sk, int val)
  59  {
  60         struct unix_sock *u = unix_sk(sk);
  61
  62 -       mutex_lock(&u->readlock);
  63 +       if (mutex_lock_interruptible(&u->readlock))
  64 +               return -EINTR;
  65 +
  66         sk->sk_peek_off = val;
  67         mutex_unlock(&u->readlock);
  68 +
  69 +       return 0;
  70  }
  71
  72