[PATCH v2] hw/net: prevent potential NULL dereference

[Oleg Sviridov]

Pointer, returned from function 'spapr_vio_find_by_reg', may be NULL and is 
dereferenced immediately after.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Oleg Sviridov <oleg.sviri...@red-soft.ru>
---
v2: Debug message added
 hw/net/spapr_llan.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/net/spapr_llan.c b/hw/net/spapr_llan.c
index ecb30b7c76..8af33d91b6 100644
--- a/hw/net/spapr_llan.c
+++ b/hw/net/spapr_llan.c
@@ -770,6 +770,12 @@ static target_ulong h_change_logical_lan_mac(PowerPCCPU 
*cpu,
     SpaprVioVlan *dev = VIO_SPAPR_VLAN_DEVICE(sdev);
     int i;
 
+    if (!dev) {
+        hcall_dprintf("H_CHANGE_LOGICAL_LAN_MAC called when "
+                      "no NIC is present\n");
+        return H_PARAMETER;
+    }
+
     for (i = 0; i < ETH_ALEN; i++) {
         dev->nicconf.macaddr.a[ETH_ALEN - i - 1] = macaddr & 0xff;
         macaddr >>= 8;
-- 
2.44.0