[Qemu-devel] [PATCH] net: filter: correctly remove filter from the list during finalization

[Jason Wang <jasowang@redhat.com>]

Qemu may crash when we want to add two filters on the same netdev but
the initialization of second fails (e.g missing parameters):

./qemu-system-x86_64 -netdev user,id=un0 \
 -object filter-buffer,id=f0,netdev=un0,interval=10 \
 -object filter-buffer,id=f1,netdev=un0
Segmentation fault (core dumped)

This is because we don't check whether or not the filter was in the
list of netdev. This patch fixes this.

Cc: Yang Hongyang <hongyang.yang@easystack.cn>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 net/filter.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/filter.c b/net/filter.c
index d2a514e..7cdbc6c 100644
--- a/net/filter.c
+++ b/net/filter.c
@@ -196,7 +196,8 @@ static void netfilter_finalize(Object *obj)
         nfc->cleanup(nf);
     }
 
-    if (nf->netdev && !QTAILQ_EMPTY(&nf->netdev->filters)) {
+    if (nf->netdev && !QTAILQ_EMPTY(&nf->netdev->filters) &&
+        nf->next.tqe_prev) {
         QTAILQ_REMOVE(&nf->netdev->filters, nf, next);
     }
     g_free(nf->netdev_id);
-- 
2.5.0