[Qemu-devel] [PATCH] net: avoid segfault in case netdev_del non-host network device

[Lei Li <lilei@linux.vnet.ibm.com>]

netdev_del assume that remove host network device.
However, when try to remove a non-host network device
by netdev_del, it will cause a segfault.

The reson is that qmp_netdev_del is not checking for
a NULL return for qemu_find_opts_err in case find_list
did not find the netdev group to delete.

Catch this and return an error.

(qemu) host_net_add user vlan=1,name=con.1,hostfwd=udp::4111-127.0.0.1:4333
(qemu) info network
hub 1
 \ con.1: type=user,net=10.0.2.0,restrict=off
hub 0
 \ user.0: type=user,net=10.0.2.0,restrict=off
 \ e1000.0: type=nic,model=e1000,macaddr=52:54:00:12:34:56
(qemu) netdev_del con.1
Segmentation fault (core dumped)

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
---
 net.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/net.c b/net.c
index ae4bc0d..cc52552 100644
--- a/net.c
+++ b/net.c
@@ -827,6 +827,7 @@ exit_err:
 void qmp_netdev_del(const char *id, Error **errp)
 {
     NetClientState *nc;
+    QemuOptsList *opt;
 
     nc = qemu_find_netdev(id);
     if (!nc) {
@@ -835,7 +836,12 @@ void qmp_netdev_del(const char *id, Error **errp)
     }
 
     qemu_del_net_client(nc);
-    qemu_opts_del(qemu_opts_find(qemu_find_opts_err("netdev", errp), id));
+    opt = qemu_find_opts_err("netdev", errp);
+    if (errp) {
+        error_setg(errp, "Failed to delete %s", id);
+        return;
+    }
+    qemu_opts_del(qemu_opts_find(opt, id));
 }
 
 void print_net_client(Monitor *mon, NetClientState *nc)
-- 
1.7.7.6