• Al Viro's avatar
    Fix double fget() in vhost_net_set_backend() · fb4554c2
    Al Viro authored
    Descriptor table is a shared resource; two fget() on the same descriptor
    may return different struct file references.  get_tap_ptr_ring() is
    called after we'd found (and pinned) the socket we'll be using and it
    tries to find the private tun/tap data structures associated with it.
    Redoing the lookup by the same file descriptor we'd used to get the
    socket is racy - we need to same struct file.
    
    Thanks to Jason for spotting a braino in the original variant of patch -
    I'd missed the use of fd == -1 for disabling backend, and in that case
    we can end up with sock == NULL and sock != oldsock.
    
    Cc: stable@kernel.org
    Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
    Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
    Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
    fb4554c2
net.c 44.5 KB