[PATCH AUTOSEL 4.19 38/38] nbd: verify socket is supported during setup

Sasha Levin
2019-10-30T15:55:59Z

From: Mike Christie <mchristi@redhat.com>

[ Upstream commit cf1b2326b734896734c6e167e41766f9cee7686a ]

nbd requires socket families to support the shutdown method so the nbd
recv workqueue can be woken up from its sock_recvmsg call. If the socket
does not support the callout we will leave recv works running or get hangs
later when the device or module is removed.

This adds a check during socket connection/reconnection to make sure the
socket being passed in supports the needed callout.

Reported-by: syzbot+24c12fa8d218ed26011a@syzkaller.appspotmail.com
Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs")
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/nbd.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index dd67a3dff93b1..cc4a642b942b2 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -932,6 +932,25 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
return ret;
}

+static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd,
+ int *err)
+{
+ struct socket *sock;
+
+ *err = 0;
+ sock = sockfd_lookup(fd, err);
+ if (!sock)
+ return NULL;
+
+ if (sock->ops->shutdown == sock_no_shutdown) {
+ dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown callout must be supported.\n");
+ *err = -EINVAL;
+ return NULL;
+ }
+
+ return sock;
+}
+
static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
bool netlink)
{
@@ -941,7 +960,7 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
struct nbd_sock *nsock;
int err;

- sock = sockfd_lookup(arg, &err);
+ sock = nbd_get_socket(nbd, arg, &err);
if (!sock)
return err;

@@ -993,7 +1012,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
int i;
int err;

- sock = sockfd_lookup(arg, &err);
+ sock = nbd_get_socket(nbd, arg, &err);
if (!sock)
return err;

--
2.20.1