floppy: Cleanup disk->queue before caling put_disk() if add_disk() was never called

add_disk() takes gendisk reference on request queue. If driver failed during
initialization and never called add_disk() then that extra reference is not
taken. That reference is put in put_disk(). floppy driver allocates the
disk, allocates queue, sets disk->queue and then relizes that floppy
controller is not present. It tries to tear down everything and tries to
put a reference down in put_disk() which was never taken.

In such error cases cleanup disk->queue before calling put_disk() so that
we never try to put down a reference which was never taken in first place.

Reported-and-tested-by: Suresh Jayaraman <sjayaraman@suse.com>
Tested-by: Dirk Gouders <gouders@et.bocholt.fh-gelsenkirchen.de>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 510fb10ec45a..401ba7833212 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4368,8 +4368,14 @@ out_unreg_blkdev:
 out_put_disk:
         while (dr--) {
                 del_timer_sync(&motor_off_timer[dr]);
-                if (disks[dr]->queue)
+                if (disks[dr]->queue) {
                         blk_cleanup_queue(disks[dr]->queue);
+                        /*
+                         * put_disk() is not paired with add_disk() and
+                         * will put queue reference one extra time. fix it.
+                         */
+                        disks[dr]->queue = NULL;
+                }
                 put_disk(disks[dr]);
         }
         return err;