hw/net/spapr: prevent potential NULL dereference

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.sviridov@red-soft.ru>
Message-ID: <20240531073636.3779559-1-oleg.sviridov@red-soft.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

diff --git a/hw/net/spapr_llan.c b/hw/net/spapr_llan.c
index ecb30b7c76bc4f89d5bb0cdac5c1dbe18a27172a..8af33d91b65e687db3238a0ae82ea408b97bd809 100644 (file)
--- 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;