[Lucid][CVE-2013-2851] block: do not pass disk names as format strings

[Luis Henriques]

From: Kees Cook <keescook at chromium.org>

BugLink: http://bugs.launchpad.net/bugs/1189832

Disk names may contain arbitrary strings, so they must not be
interpreted as format strings.  It seems that only md allows arbitrary
strings to be used for disk names, but this could allow for a local
memory corruption from uid 0 into ring 0.

CVE-2013-2851

Signed-off-by: Kees Cook <keescook at chromium.org>
Cc: Jens Axboe <axboe at kernel.dk>
Cc: <stable at vger.kernel.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(back ported from commit ffc8b30866879ed9ba62bd0a86fecdbd51cd3d19)

[ luis: backported to Lucid kernel:
  - adjusted context
  - register_disk() is in fs/partitions/check.c
  - dropped changes to osd_probe() as the issue was introduced only
    with commit d6ae433 ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/block/nbd.c   | 3 ++-
 fs/partitions/check.c | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7b83e7b..cf5d83a 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -655,7 +655,8 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
 
 		mutex_unlock(&lo->tx_lock);
 
-		thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
+		thread = kthread_create(nbd_thread, lo, "%s",
+					lo->disk->disk_name);
 		if (IS_ERR(thread)) {
 			mutex_lock(&lo->tx_lock);
 			return PTR_ERR(thread);
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 7b685e1..aa90d88 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -476,7 +476,7 @@ void register_disk(struct gendisk *disk)
 
 	ddev->parent = disk->driverfs_dev;
 
-	dev_set_name(ddev, disk->disk_name);
+	dev_set_name(ddev, "%s", disk->disk_name);
 
 	/* delay uevents, until we scanned partition table */
 	dev_set_uevent_suppress(ddev, 1);
-- 
1.8.1.2