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block: fix use-after-free in disk_part_iter_next

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commit aebf5db917055b38f4945ed6d621d9f07a44ff30 upstream.

Make sure that bdgrab() is done on the 'block_device' instance before
referring to it for avoiding use-after-free.

Cc: <stable@vger.kernel.org>
Reported-by: syzbot+825f0f9657d4e528046e@syzkaller.appspotmail.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ming Lei 2020-12-21 12:33:35 +08:00 committed by Greg Kroah-Hartman
parent 61e8c02ae6
commit 481097d661
1 changed files with 6 additions and 3 deletions
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9
block/genhd.c
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@ -256,14 +256,17 @@ struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
part = rcu_dereference(ptbl->part[piter->idx]);
if (!part)
continue;
get_device(part_to_dev(part));
piter->part = part;
if (!part_nr_sects_read(part) &&
!(piter->flags & DISK_PITER_INCL_EMPTY) &&
!(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
piter->idx == 0))
piter->idx == 0)) {
put_device(part_to_dev(part));
piter->part = NULL;
continue;
}
get_device(part_to_dev(part));
piter->part = part;
piter->idx += inc;
break;
}