[PATCH 1/2] ataflop: fix error handling in atari_floppy_init()

[Dan Carpenter]

Smatch complains that there is an off by one if the allocation fails in:

        DMABuffer = atari_stram_alloc(BUFFER_SIZE+512, "ataflop");

In that situation, "i" would be point to one element beyond the end of
the unit[] array.

There is a second bug because the error handling calls
blk_mq_free_tag_set(&unit[i].tag_set); regardless of whether
"disk->queue" is NULL or non-NULL.  So if blk_mq_init_sq_queue() fails,
then that means unit[i].tag_set->tags is NULL and it leads to an Oops.

It's easiest to call put_disk() before the goto to clean up the partial
iteration.  Then the earlier unit[] elements are fully allocated so we
can remove the checks whether "disk->queue" is NULL and the code is
simpler.

Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
---

I hope the Atari floppy disk users are appropriately grateful for all
the love and effort we put into their software...

 drivers/block/ataflop.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
index f88b4c26d422..313064b1005c 100644
--- a/drivers/block/ataflop.c
+++ b/drivers/block/ataflop.c
@@ -1982,6 +1982,7 @@ static int __init atari_floppy_init (void)
                                                           &ataflop_mq_ops, 2,
                                                           
BLK_MQ_F_SHOULD_MERGE);
                if (IS_ERR(unit[i].disk->queue)) {
+                       put_disk(unit[i].disk);
                        ret = PTR_ERR(unit[i].disk->queue);
                        unit[i].disk->queue = NULL;
                        goto err;
@@ -2033,18 +2034,13 @@ static int __init atari_floppy_init (void)
        return 0;
 
 err:
-       do {
+       while (--i >= 0) {
                struct gendisk *disk = unit[i].disk;
 
-               if (disk) {
-                       if (disk->queue) {
-                               blk_cleanup_queue(disk->queue);
-                               disk->queue = NULL;
-                       }
-                       blk_mq_free_tag_set(&unit[i].tag_set);
-                       put_disk(unit[i].disk);
-               }
-       } while (i--);
+               blk_cleanup_queue(disk->queue);
+               blk_mq_free_tag_set(&unit[i].tag_set);
+               put_disk(unit[i].disk);
+       }
 
        unregister_blkdev(FLOPPY_MAJOR, "fd");
        return ret;
-- 
2.11.0