nbd: prevent sock_xmit from attempting to use a NULL socket

ffc41cf8 · Mike Snitzer <[email protected]> · 2008-04-02 13:04:47 -07:00

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 <[email protected]>
Cc: Paul Clements <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: ffc41cf8dbb1b895a87daf47d0e5bf6dfbfcab4c
Parents: f2b2ea69

Changes

1 files changed · +6 −0

File	Status	Add	Del	Content
drivers/block/nbd.c	modified	+6	−0	View file

drivers/block/nbd.c

View file

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b53fdb0..60cc543 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -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));