[Qemu-devel] [PATCH v3] net: Fix a potential segfault

[Lin Ma <lma@suse.com>]

If user forgets to provide any backend types for '-netdev' in qemu CLI,
It triggers seg fault.

e.g.

Expected:
$ qemu -netdev id=net0
qemu-system-x86_64: Parameter 'type' is missing

Actual:
$ qemu -netdev id=net0
Segmentation fault (core dumped)

Signed-off-by: Lin Ma <lma@suse.com>
---
 net/net.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/net.c b/net/net.c
index efb9eaf779..2a3133990c 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1093,7 +1093,9 @@ static int net_client_init(QemuOpts *opts, bool is_netdev, Error **errp)
     int ret = -1;
     Visitor *v = opts_visitor_new(opts);
 
-    if (is_netdev && is_help_option(qemu_opt_get(opts, "type"))) {
+    const char *type = qemu_opt_get(opts, "type");
+
+    if (is_netdev && type && is_help_option(type)) {
         show_netdevs();
         exit(0);
     } else {
-- 
2.16.2