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dm zoned: fix invalid memory access 

Commit 75d66ffb48 ("dm zoned: properly
handle backing device failure") triggers a coverity warning:

*** CID 1452808:  Memory - illegal accesses  (USE_AFTER_FREE)
/drivers/md/dm-zoned-target.c: 137 in dmz_submit_bio()
131             clone->bi_private = bioctx;
132
133             bio_advance(bio, clone->bi_iter.bi_size);
134
135             refcount_inc(&bioctx->ref);
136             generic_make_request(clone);
>>>     CID 1452808:  Memory - illegal accesses  (USE_AFTER_FREE)
>>>     Dereferencing freed pointer "clone".
137             if (clone->bi_status == BLK_STS_IOERR)
138                     return -EIO;
139
140             if (bio_op(bio) == REQ_OP_WRITE && dmz_is_seq(zone))
141                     zone->wp_block += nr_blocks;
142

The "clone" bio may be processed and freed before the check
"clone->bi_status == BLK_STS_IOERR" - so this check can access invalid
memory.

Fixes: 75d66ffb48 ("dm zoned: properly handle backing device failure")
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2019-08-26 02:41:17 -04:00 committed by Mike Snitzer
parent 88cd3e6cfa
commit 0c8e9c2d66
1 changed files with 0 additions and 2 deletions
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2
drivers/md/dm-zoned-target.c
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@ -134,8 +134,6 @@ static int dmz_submit_bio(struct dmz_target *dmz, struct dm_zone *zone,
refcount_inc(&bioctx->ref);
generic_make_request(clone);
if (clone->bi_status == BLK_STS_IOERR)
return -EIO;
if (bio_op(bio) == REQ_OP_WRITE && dmz_is_seq(zone))
zone->wp_block += nr_blocks;