commit ce960aa9062a407d0ca15aee3dcd3bd84a4e24f9
author Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Fri Sep 29 18:22:55 2017 +0300
committer Max Reitz <mreitz@redhat.com> Fri Oct 06 16:30:48 2017 +0200
tree 1ba071735ea70c9095cd9ab33d6b8a32f21585f7
parent 163bc39d2c2921430e5c23f4d0a0966d62f67a02

block/mirror: check backing in bdrv_mirror_top_flush

Backing may be zero after failed bdrv_append in mirror_start_job,
which leads to SIGSEGV.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20170929152255.5431-1-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/mirror.c

diff --git a/block/mirror.c b/block/mirror.c
index 3b6f0c5..153758c 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1041,6 +1041,10 @@
 
 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs)
 {
+    if (bs->backing == NULL) {
+        /* we can be here after failed bdrv_append in mirror_start_job */
+        return 0;
+    }
     return bdrv_co_flush(bs->backing->bs);
 }