[Qemu-devel] [PATCH] filter-buffer: fix segfault while start qemu with status=off property

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

After commit 338d3f, we support 'status' property for filter object.
The segfault can be triggered by starting qemu with 'status=off' property
for filter, when the s->incoming_queue is NULL, we reference it directly
in qemu_net_queue_flush().

Let's check the value of 's->incoming_queue' before calling
qemu_net_queue_flush().

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 net/filter-buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/filter-buffer.c b/net/filter-buffer.c
index cc6bd94..79e2ce3 100644
--- a/net/filter-buffer.c
+++ b/net/filter-buffer.c
@@ -34,7 +34,7 @@ static void filter_buffer_flush(NetFilterState *nf)
 {
     FilterBufferState *s = FILTER_BUFFER(nf);
 
-    if (!qemu_net_queue_flush(s->incoming_queue)) {
+    if (s->incoming_queue && !qemu_net_queue_flush(s->incoming_queue)) {
         /* Unable to empty the queue, purge remaining packets */
         qemu_net_queue_purge(s->incoming_queue, nf->netdev);
     }
-- 
1.8.3.1