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Subject[PATCH] block: avoid null pointer dereference on null disk
Date
From: Colin Ian King <colin.king@canonical.com>

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")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
block/genhd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index d85dcc701d76..42908a7186cd 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;
}
--
2.14.1
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