[Nbd] [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 <snitzer@...17...>
Cc: Paul Clements <paul.clements@...124...>
---
drivers/block/nbd.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b53fdb0..bd3c50b 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));
--
1.5.3.4
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