nbd: prevent sock_xmit from attempting to use a NULL socket

NBD does not protect the nbd_device's socket from becoming NULL during
receives.

This closes a race with the NBD_CLEAR_SOCK ioctl (nbd-client -d) setting
the nbd_device's socket to NULL right before NBD calls sock_xmit.

Signed-off-by: Mike Snitzer <snitzer@gmail.com>
Cc: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Snitzer 2008-04-02 13:04:47 -07:00 committed by Linus Torvalds
parent f2b2ea692e
commit ffc41cf8db

View File

@ -153,6 +153,12 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
struct kvec iov;
sigset_t blocked, oldset;
if (unlikely(!sock)) {
printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
lo->disk->disk_name, (send ? "send" : "recv"));
return -EINVAL;
}
/* Allow interception of SIGKILL only
* Don't allow other signals to interrupt the transmission */
siginitsetinv(&blocked, sigmask(SIGKILL));