RDMA/irdma: avoid invalid read in irdma_net_event

In the Linux kernel, the following vulnerability has been resolved: RDMA/irdma: avoid invalid read in irdma_net_event irdma_net_event() should not dereference anything from "neigh" (alias "ptr") until it has checked that the event is NETEVENT_NEIGH_UPDATE. Other events come with different structures pointed to by "ptr" and they may be smaller than struct neighbour. Move the read of neigh->dev under the NETEVENT_NEIGH_UPDATE case. The bug is mostly harmless, but it triggers KASAN on debug kernels: BUG: KASAN: stack-out-of-bounds in irdma_net_event+0x32e/0x3b0 [irdma] Read of size 8 at addr ffffc900075e07f0 by task kworker/27:2/542554 CPU: 27 PID: 542554 Comm: kworker/27:2 Kdump: loaded Not tainted 5.14.0-630.el9.x86_64+debug #1 Hardware name: [...] Workqueue: events rt6_probe_deferred Call Trace: <IRQ> dump_stack_lvl+0x60/0xb0 print_address_description.constprop.0+0x2c/0x3f0 print_report+0xb4/0x270 kasan_report+0x92/0xc0 irdma_net_event+0x32e/0x3b0 [irdma] notifier_call_chain+0x9e/0x180 atomic_notifier_call_chain+0x5c/0x110 rt6_do_redirect+0xb91/0x1080 tcp_v6_err+0xe9b/0x13e0 icmpv6_notify+0x2b2/0x630 ndisc_redirect_rcv+0x328/0x530 icmpv6_rcv+0xc16/0x1360 ip6_protocol_deliver_rcu+0xb84/0x12e0 ip6_input_finish+0x117/0x240 ip6_input+0xc4/0x370 ipv6_rcv+0x420/0x7d0 __netif_receive_skb_one_core+0x118/0x1b0 process_backlog+0xd1/0x5d0 __napi_poll.constprop.0+0xa3/0x440 net_rx_action+0x78a/0xba0 handle_softirqs+0x2d4/0x9c0 do_softirq+0xad/0xe0 </IRQ>

Where it's fixed