block: Fix NULL dereference on empty drive error

blk_error_action() sends a BLOCK_IO_ERROR QMP event which includes the node name of its root node. If the BlockBackend represents an empty drive, there is no root node, so we should not try to access its node name. Make the field optional in the event and include it only when the BlockBackend isn't empty. Signed-off-by: Kevin Wolf <[email protected]> Reviewed-by: Eric Blake <[email protected]>
n64decomp · Mar 5, 2018 · bfe1a14 · bfe1a14
1 parent 9d9b4b6
commit bfe1a14
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Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/block/block-backend.c b/block/block-backend.c
@@ -1615,10 +1615,11 @@ static void send_qmp_error_event(BlockBackend *blk,
                                  bool is_read, int error)
 {
     IoOperationType optype;
+    BlockDriverState *bs = blk_bs(blk);
 
     optype = is_read ? IO_OPERATION_TYPE_READ : IO_OPERATION_TYPE_WRITE;
-    qapi_event_send_block_io_error(blk_name(blk),
-                                   bdrv_get_node_name(blk_bs(blk)), optype,
+    qapi_event_send_block_io_error(blk_name(blk), !!bs,
+                                   bs ? bdrv_get_node_name(bs) : NULL, optype,
                                    action, blk_iostatus_is_enabled(blk),
                                    error == ENOSPC, strerror(error),
                                    &error_abort);

diff --git a/qapi/block-core.json b/qapi/block-core.json
@@ -3676,7 +3676,8 @@
 #
 # @node-name: node name. Note that errors may be reported for the root node
 #             that is directly attached to a guest device rather than for the
-#             node where the error occurred. (Since: 2.8)
+#             node where the error occurred. The node name is not present if
+#             the drive is empty. (Since: 2.8)
 #
 # @operation: I/O operation
 #
@@ -3707,7 +3708,8 @@
 #
 ##
 { 'event': 'BLOCK_IO_ERROR',
-  'data': { 'device': 'str', 'node-name': 'str', 'operation': 'IoOperationType',
+  'data': { 'device': 'str', '*node-name': 'str',
+            'operation': 'IoOperationType',
             'action': 'BlockErrorAction', '*nospace': 'bool',
             'reason': 'str' } }