[bug report] octeontx2-pf: Ntuple filters support for VF netdev

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Rakesh Babu,

The patch 3cffaed2136c: "octeontx2-pf: Ntuple filters support for VF
netdev" from Aug 17, 2021, leads to the following Smatch static
checker warning:

    drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_fs.c:1247 rvu_mbox_handler_npc_install_flow()
    error: uninitialized symbol 'nixlf'.

    drivers/net/ethernet/marvell/octeontx2/af/rvu_npc.c:392 npc_get_default_entry_action()
    error: uninitialized symbol 'nixlf'.

drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_fs.c
    1154 int rvu_mbox_handler_npc_install_flow(struct rvu *rvu,
    1155                                       struct npc_install_flow_req *req,
    1156                                       struct npc_install_flow_rsp *rsp)
    1157 {
    1158         bool from_vf = !!(req->hdr.pcifunc & RVU_PFVF_FUNC_MASK);
    1159         struct rvu_switch *rswitch = &rvu->rswitch;
    1160         int blkaddr, nixlf, err;
                              ^^^^^
    1161         struct rvu_pfvf *pfvf;
    1162         bool pf_set_vfs_mac = false;
    1163         bool enable = true;
    1164         u16 target;
    1165 
    1166         blkaddr = rvu_get_blkaddr(rvu, BLKTYPE_NPC, 0);
    1167         if (blkaddr < 0) {
    1168                 dev_err(rvu->dev, "%s: NPC block not implemented\n", __func__);
    1169                 return NPC_MCAM_INVALID_REQ;
    1170         }
    1171 
    1172         if (!is_npc_interface_valid(rvu, req->intf))
    1173                 return NPC_FLOW_INTF_INVALID;
    1174 
    1175         if (from_vf && req->default_rule)
    1176                 return NPC_FLOW_VF_PERM_DENIED;
    1177 
    1178         /* Each PF/VF info is maintained in struct rvu_pfvf.
    1179          * rvu_pfvf for the target PF/VF needs to be retrieved
    1180          * hence modify pcifunc accordingly.
    1181          */
    1182 
    1183         /* AF installing for a PF/VF */
    1184         if (!req->hdr.pcifunc)
    1185                 target = req->vf;
    1186         /* PF installing for its VF */
    1187         else if (!from_vf && req->vf) {
    1188                 target = (req->hdr.pcifunc & ~RVU_PFVF_FUNC_MASK) | req->vf;
    1189                 pf_set_vfs_mac = req->default_rule &&
    1190                                 (req->features & BIT_ULL(NPC_DMAC));
    1191         }
    1192         /* msg received from PF/VF */
    1193         else
    1194                 target = req->hdr.pcifunc;
    1195 
    1196         /* ignore chan_mask in case pf func is not AF, revisit later */
    1197         if (!is_pffunc_af(req->hdr.pcifunc))
    1198                 req->chan_mask = 0xFFF;
    1199 
    1200         err = npc_check_unsupported_flows(rvu, req->features, req->intf);
    1201         if (err)
    1202                 return NPC_FLOW_NOT_SUPPORTED;
    1203 
    1204         pfvf = rvu_get_pfvf(rvu, target);
    1205 
    1206         /* PF installing for its VF */
    1207         if (req->hdr.pcifunc && !from_vf && req->vf)
    1208                 set_bit(PF_SET_VF_CFG, &pfvf->flags);
    1209 
    1210         /* update req destination mac addr */
    1211         if ((req->features & BIT_ULL(NPC_DMAC)) && is_npc_intf_rx(req->intf) &&
    1212             is_zero_ether_addr(req->packet.dmac)) {
    1213                 ether_addr_copy(req->packet.dmac, pfvf->mac_addr);
    1214                 eth_broadcast_addr((u8 *)&req->mask.dmac);
    1215         }
    1216 
    1217         /* Proceed if NIXLF is attached or not for TX rules */
    1218         err = nix_get_nixlf(rvu, target, &nixlf, NULL);
    1219         if (err && is_npc_intf_rx(req->intf) && !pf_set_vfs_mac)
    1220                 return NPC_FLOW_NO_NIXLF;

If nix_get_nixlf() fails then "nixlf" is not necessarily initialized and
then if is_npc_intf_rx() is true or pf_set_vfs_mac is false then this
will not return.

    1221 
    1222         /* don't enable rule when nixlf not attached or initialized */
    1223         if (!(is_nixlf_attached(rvu, target) &&
    1224               test_bit(NIXLF_INITIALIZED, &pfvf->flags)))
    1225                 enable = false;
    1226 
    1227         /* Packets reaching NPC in Tx path implies that a
    1228          * NIXLF is properly setup and transmitting.
    1229          * Hence rules can be enabled for Tx.
    1230          */
    1231         if (is_npc_intf_tx(req->intf))
    1232                 enable = true;
    1233 
    1234         /* Do not allow requests from uninitialized VFs */
    1235         if (from_vf && !enable)
    1236                 return NPC_FLOW_VF_NOT_INIT;
    1237 
    1238         /* PF sets VF mac & VF NIXLF is not attached, update the mac addr */
    1239         if (pf_set_vfs_mac && !enable) {
    1240                 ether_addr_copy(pfvf->default_mac, req->packet.dmac);
    1241                 ether_addr_copy(pfvf->mac_addr, req->packet.dmac);
    1242                 set_bit(PF_SET_VF_MAC, &pfvf->flags);
    1243                 return 0;
    1244         }
    1245 
    1246         mutex_lock(&rswitch->switch_lock);
--> 1247         err = npc_install_flow(rvu, blkaddr, target, nixlf, pfvf,
                                                              ^^^^^
Potentially passing an uninitialized value.

    1248                                req, rsp, enable, pf_set_vfs_mac);
    1249         mutex_unlock(&rswitch->switch_lock);
    1250 
    1251         return err;
    1252 }

regards,
dan carpenter