From 9fbe06ec1dad1ffc7a2bcc138b7dbd6bf83e36cd Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 15 Mar 2019 18:10:02 +0100
Subject: [PATCH 006/163] block: Fix use after free error in
 bdrv_open_inherit()

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20190315181010.14964-7-kwolf@redhat.com>
Patchwork-id: 84883
O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 06/14] block: Fix use after free error in bdrv_open_inherit()
Bugzilla: 1685989
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Alberto Garcia <berto@igalia.com>

When a block device is opened with BDRV_O_SNAPSHOT and the
bdrv_append_temp_snapshot() call fails then the error code path tries
to unref the already destroyed 'options' QDict.

This can be reproduced easily by setting TMPDIR to a location where
the QEMU process can't write:

   $ TMPDIR=/nonexistent $QEMU -drive driver=null-co,snapshot=on

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 8961be33e8ca7e809c603223803ea66ef7ea5be7)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block.c b/block.c
index b31124c..25b3fe5 100644
--- a/block.c
+++ b/block.c
@@ -2834,6 +2834,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
     bdrv_parent_cb_change_media(bs, true);
 
     qobject_unref(options);
+    options = NULL;
 
     /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
      * temporary snapshot afterwards. */
-- 
1.8.3.1