[Qemu-block] [PULL 11/14] block: Null pointer dereference in blk_root_get_parent_desc()

[Kevin Wolf]

From: Liam Merwick <liam.merw...@oracle.com>

The dev_id returned by the call to blk_get_attached_dev_id() in
blk_root_get_parent_desc() can be NULL (an internal call to
object_get_canonical_path may have returned NULL).

Instead of just checking this case before before dereferencing,
adjust blk_get_attached_dev_id() to return the empty string if no
object path can be found (similar to the case when blk->dev is NULL
and an empty string is returned).

Signed-off-by: Liam Merwick <liam.merw...@oracle.com>
Message-id: 1541453919-25973-3-git-send-email-liam.merw...@oracle.com
Reviewed-by: Max Reitz <mre...@redhat.com>
Signed-off-by: Max Reitz <mre...@redhat.com>
---
 block/block-backend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 2a8f3b55f8..60d37a0c3d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -918,7 +918,8 @@ char *blk_get_attached_dev_id(BlockBackend *blk)
     } else if (dev->id) {
         return g_strdup(dev->id);
     }
-    return object_get_canonical_path(OBJECT(dev));
+
+    return object_get_canonical_path(OBJECT(dev)) ?: g_strdup("");
 }
 
 /*
-- 
2.19.1