From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 6 Nov 2010 00:45:59 +0000 (-0700)
Subject: floppy: fix use-after-free in module load failure path
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=c093ee4f07f46d3a835841cafa07514fa94878d2;p=deliverable%2Flinux.git

floppy: fix use-after-free in module load failure path

Commit 488211844e0c ("floppy: switch to one queue per drive instead of
sharing a queue") introduced a use-after-free.  We do "put_disk()" on
the disk device _before_ we then clean up the queue associated with that
disk.

Move the put_disk() down to avoid dereferencing a free'd data structure.

Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Reported-and-tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 767107cce982..8f19b380ca83 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4363,9 +4363,9 @@ out_unreg_blkdev:
 out_put_disk:
 	while (dr--) {
 		del_timer(&motor_off_timer[dr]);
-		put_disk(disks[dr]);
 		if (disks[dr]->queue)
 			blk_cleanup_queue(disks[dr]->queue);
+		put_disk(disks[dr]);
 	}
 	return err;
 }