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[Qemu-devel] [PATCH v4 3/8] block: Null pointer dereference in blk_root_


From: Liam Merwick
Subject: [Qemu-devel] [PATCH v4 3/8] block: Null pointer dereference in blk_root_get_parent_desc()
Date: Fri, 19 Oct 2018 21:39:01 +0100

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 <address@hidden>
---
 block/block-backend.c | 6 +++++-
 dtc                   | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index dc0cd5772413..e628920f3cd8 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -909,6 +909,7 @@ void *blk_get_attached_dev(BlockBackend *blk)
 char *blk_get_attached_dev_id(BlockBackend *blk)
 {
     DeviceState *dev;
+    char *dev_id;
 
     assert(!blk->legacy_dev);
     dev = blk->dev;
@@ -918,7 +919,10 @@ char *blk_get_attached_dev_id(BlockBackend *blk)
     } else if (dev->id) {
         return g_strdup(dev->id);
     }
-    return object_get_canonical_path(OBJECT(dev));
+
+    dev_id = object_get_canonical_path(OBJECT(dev));
+
+    return dev_id ? dev_id : g_strdup("");
 }
 
 /*
diff --git a/dtc b/dtc
index 88f18909db73..e54388015af1 160000
--- a/dtc
+++ b/dtc
@@ -1 +1 @@
-Subproject commit 88f18909db731a627456f26d779445f84e449536
+Subproject commit e54388015af1fb4bf04d0bca99caba1074d9cc42
-- 
1.8.3.1




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