CVE-2022-50679: 
Linux Kernel vulnerability analysis and mitigation

In the Linux kernel, the following vulnerability has been resolved:

i40e: Fix DMA mappings leak

During reallocation of RX buffers, new DMA mappings are created for those buffers.

steps for reproduction: while : do for ((i=0; i<=8160; i=i+32)) do ethtool -G enp130s0f0 rx $i tx $i sleep 0.5 ethtool -g enp130s0f0 done done

This resulted in crash: i40e 0000:01:00.1: Unable to allocate memory for the Rx descriptor ring, size=65536 Driver BUG WARNING: CPU: 0 PID: 4300 at net/core/xdp.c:141 xdp_rxq_info_unreg+0x43/0x50 Call Trace: i40e_free_rx_resources+0x70/0x80 [i40e] i40e_set_ringparam+0x27c/0x800 [i40e] ethnl_set_rings+0x1b2/0x290 genl_family_rcv_msg_doit.isra.15+0x10f/0x150 genl_family_rcv_msg+0xb3/0x160 ? rings_fill_reply+0x1a0/0x1a0 genl_rcv_msg+0x47/0x90 ? genl_family_rcv_msg+0x160/0x160 netlink_rcv_skb+0x4c/0x120 genl_rcv+0x24/0x40 netlink_unicast+0x196/0x230 netlink_sendmsg+0x204/0x3d0 sock_sendmsg+0x4c/0x50 __sys_sendto+0xee/0x160 ? handle_mm_fault+0xbe/0x1e0 ? syscall_trace_enter+0x1d3/0x2c0 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x5b/0x1a0 entry_SYSCALL_64_after_hwframe+0x65/0xca RIP: 0033:0x7f5eac8b035b Missing register, driver bug WARNING: CPU: 0 PID: 4300 at net/core/xdp.c:119 xdp_rxq_info_unreg_mem_model+0x69/0x140 Call Trace: xdp_rxq_info_unreg+0x1e/0x50 i40e_free_rx_resources+0x70/0x80 [i40e] i40e_set_ringparam+0x27c/0x800 [i40e] ethnl_set_rings+0x1b2/0x290 genl_family_rcv_msg_doit.isra.15+0x10f/0x150 genl_family_rcv_msg+0xb3/0x160 ? rings_fill_reply+0x1a0/0x1a0 genl_rcv_msg+0x47/0x90 ? genl_family_rcv_msg+0x160/0x160 netlink_rcv_skb+0x4c/0x120 genl_rcv+0x24/0x40 netlink_unicast+0x196/0x230 netlink_sendmsg+0x204/0x3d0 sock_sendmsg+0x4c/0x50 __sys_sendto+0xee/0x160 ? handle_mm_fault+0xbe/0x1e0 ? syscall_trace_enter+0x1d3/0x2c0 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x5b/0x1a0 entry_SYSCALL_64_after_hwframe+0x65/0xca RIP: 0033:0x7f5eac8b035b

This was caused because of new buffers with different RX ring count should substitute older ones, but those buffers were freed in i40e_configure_rx_ring and reallocated again with i40e_alloc_rx_bi, thus kfree on rx_bi caused leak of already mapped DMA.

Fix this by reallocating ZC with rx_bi_zc struct when BPF program loads. Additionally reallocate back to rx_bi when BPF program unloads.

If BPF program is loaded/unloaded and XSK pools are created, reallocate RX queues accordingly in XSP_SETUP_XSK_POOL handler.