From ffc41cf8dbb1b895a87daf47d0e5bf6dfbfcab4c Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 2 Apr 2008 13:04:47 -0700 Subject: [PATCH] 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 Cc: Paul Clements Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/nbd.c | 6 ++++++ 1 file changed, 6 insertions(+) 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)); -- 2.7.4