block: fix memleaks in bdrv_refresh_filename

If we call the qmp 'query-block' while qemu is working on
'block-commit', it will cause memleaks, the memory leak stack is as
follow:

Indirect leak of 12360 byte(s) in 3 object(s) allocated from:
    #0 0x7f80f0b6d970 in __interceptor_calloc (/lib64/libasan.so.5+0xef970)
    kata-containers#1 0x7f80ee86049d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5249d)
    kata-containers#2 0x55ea95b5bb67 in qdict_new /mnt/sdb/qemu-4.2.0-rc0/qobject/qdict.c:29
    kata-containers#3 0x55ea956cd043 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6427
    kata-containers#4 0x55ea956cc950 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6399
    kata-containers#5 0x55ea956cc950 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6399
    kata-containers#6 0x55ea956cc950 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6399
    kata-containers#7 0x55ea958818ea in bdrv_block_device_info /mnt/sdb/qemu-4.2.0-rc0/block/qapi.c:56
    kata-containers#8 0x55ea958879de in bdrv_query_info /mnt/sdb/qemu-4.2.0-rc0/block/qapi.c:392
    kata-containers#9 0x55ea9588b58f in qmp_query_block /mnt/sdb/qemu-4.2.0-rc0/block/qapi.c:578
    kata-containers#10 0x55ea95567392 in qmp_marshal_query_block qapi/qapi-commands-block-core.c:95

Indirect leak of 4120 byte(s) in 1 object(s) allocated from:
    #0 0x7f80f0b6d970 in __interceptor_calloc (/lib64/libasan.so.5+0xef970)
    kata-containers#1 0x7f80ee86049d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5249d)
    kata-containers#2 0x55ea95b5bb67 in qdict_new /mnt/sdb/qemu-4.2.0-rc0/qobject/qdict.c:29
    kata-containers#3 0x55ea956cd043 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6427
    kata-containers#4 0x55ea956cc950 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6399
    kata-containers#5 0x55ea956cc950 in bdrv_refresh_filename /mnt/sdb/qemu-4.2.0-rc0/block.c:6399
    kata-containers#6 0x55ea9569f301 in bdrv_backing_attach /mnt/sdb/qemu-4.2.0-rc0/block.c:1064
    kata-containers#7 0x55ea956a99dd in bdrv_replace_child_noperm /mnt/sdb/qemu-4.2.0-rc0/block.c:2283
    kata-containers#8 0x55ea956b9b53 in bdrv_replace_node /mnt/sdb/qemu-4.2.0-rc0/block.c:4196
    kata-containers#9 0x55ea956b9e49 in bdrv_append /mnt/sdb/qemu-4.2.0-rc0/block.c:4236
    kata-containers#10 0x55ea958c3472 in commit_start /mnt/sdb/qemu-4.2.0-rc0/block/commit.c:306
    qemu#11 0x55ea94b68ab0 in qmp_block_commit /mnt/sdb/qemu-4.2.0-rc0/blockdev.c:3459
    qemu#12 0x55ea9556a7a7 in qmp_marshal_block_commit qapi/qapi-commands-block-core.c:407

Fixes: bb808d5
Reported-by: Euler Robot <[email protected]>
Signed-off-by: Pan Nengyuan <[email protected]>
Message-id: [email protected]
Signed-off-by: Max Reitz <[email protected]>

block.c

@@ -6442,6 +6442,7 @@ void bdrv_refresh_filename(BlockDriverState *bs)
                 child->bs->exact_filename);
         pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
 
+        qobject_unref(bs->full_open_options);
         bs->full_open_options = qobject_ref(child->bs->full_open_options);
 
         return;