On Mon, 26 Aug 2019, Damien Le Moal wrote:
> On 2019/08/26 15:41, Mikulas Patocka wrote:
> > The patch 75d66ffb48efb30f2dd42f041ba8b39c5b2bd115 ("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.
> >
> > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
We should also append this line:
Fixes: 75d66ffb48ef ("dm zoned: properly handle backing device failure")
Mikulas
> > ---
> > drivers/md/dm-zoned-target.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > Index: linux-2.6/drivers/md/dm-zoned-target.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/md/dm-zoned-target.c 2019-08-26 08:30:30.000000000 +0200
> > +++ linux-2.6/drivers/md/dm-zoned-target.c 2019-08-26 08:36:23.000000000 +0200
> > @@ -134,8 +134,6 @@ static int dmz_submit_bio(struct dmz_tar
> >
> > 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;
> >
>
> Argh... Indeed. Thanks Mikulas.
>
> Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxx>
>
> --
> Damien Le Moal
> Western Digital Research
>
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