From: Colin Ian King <colin.king@canonical.com>
Date: Mon, 6 Nov 2017 17:53:53 +0000
Subject: block: avoid null pointer dereference on null disk
Git-commit: f0fba398fec65ff5a2e1bf8ae62718ec0450abaf
Patch-Mainline: v4.15-rc1
References: FATE#323952, FATE#322506
It is possible that the pointer disk can be null and hence
we can get a null pointer deference when accessing disk->flags.
Add a null pointer check to avoid the dereference.
Detected by CoverityScan, CID#1461133 ("Explicit null dereferenced")
Fixes: 8ddcd653257c ("block: introduce GENHD_FL_HIDDEN")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/genhd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/genhd.c b/block/genhd.c
index 3de1671..997e598 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -798,7 +798,7 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
spin_unlock_bh(&ext_devt_lock);
}
- if (unlikely(disk->flags & GENHD_FL_HIDDEN)) {
+ if (disk && unlikely(disk->flags & GENHD_FL_HIDDEN)) {
put_disk(disk);
disk = NULL;
}
--
1.8.5.6