Make sure that bdgrab() is done on the 'block_device' instance before
referring to it for avoiding use-after-free.
Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: syzbot+825f0f9657d4e528046e@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/genhd.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index b84b8671e627..2df3c5b1c9c8 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -244,15 +244,18 @@ struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
part = rcu_dereference(ptbl->part[piter->idx]);
if (!part)
continue;
+ piter->part = bdgrab(part);
+ if (!piter->part)
+ continue;
if (!bdev_nr_sectors(part) &&
!(piter->flags & DISK_PITER_INCL_EMPTY) &&
!(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
- piter->idx == 0))
+ piter->idx == 0)) {
+ bdput(piter->part);
+ piter->part = NULL;
continue;
+ }
- piter->part = bdgrab(part);
- if (!piter->part)
- continue;
piter->idx += inc;
break;
}
--
2.28.0
