[PATCH] Fix NULL pointer dereference in bl_free_device().

From	Artem Savkov <asavkov@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH] Fix NULL pointer dereference in bl_free_device().
Date	2016-07-19 13:40 +0200
Message-ID	<rWBxv-3r9-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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When bl_parse_deviceid() fails in bl_alloc_deviceid_node() on
blkdev_get_by_*() step we get an pnfs_block_dev struct that is
uninitialized except for bdev field which is set to whatever error
blkdev_get_by_*() returns.  bl_free_device() then tries to call
blkdev_put() if bdev is not 0 resulting in a wrong pointer dereference.

Fixing this by making sure bdev is not an error code in bl_free_device().

Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
 fs/nfs/blocklayout/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
index 118252f..7db3af0 100644
--- a/fs/nfs/blocklayout/dev.c
+++ b/fs/nfs/blocklayout/dev.c
@@ -33,7 +33,7 @@ bl_free_device(struct pnfs_block_dev *dev)
 				pr_err("failed to unregister PR key.\n");
 		}
 
-		if (dev->bdev)
+		if (dev->bdev && !IS_ERR(dev->bdev))
 			blkdev_put(dev->bdev, FMODE_READ | FMODE_WRITE);
 	}
 }
-- 
2.5.5

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[PATCH] Fix NULL pointer dereference in bl_free_device(). Artem Savkov <asavkov@redhat.com> - 2016-07-19 13:40 +0200
  Re: [PATCH] Fix NULL pointer dereference in bl_free_device(). Anna Schumaker <Anna.Schumaker@netapp.com> - 2016-07-19 17:30 +0200
    [PATCH v2] Fix NULL pointer dereference in bl_free_device(). Artem Savkov <asavkov@redhat.com> - 2016-07-19 17:50 +0200
      Re: [PATCH v2] Fix NULL pointer dereference in bl_free_device(). Christoph Hellwig <hch@lst.de> - 2016-07-21 10:10 +0200
        [PATCH v3] Fix NULL pointer dereference in bl_free_device(). Artem Savkov <asavkov@redhat.com> - 2016-07-21 13:40 +0200
          Re: [PATCH v3] Fix NULL pointer dereference in bl_free_device(). "Benjamin Coddington" <bcodding@redhat.com> - 2016-07-21 14:30 +0200
  Re: [PATCH] Fix NULL pointer dereference in bl_free_device(). Anna Schumaker <Anna.Schumaker@netapp.com> - 2016-07-19 17:30 +0200

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