tipc: fix UAF in error path

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

tipc: fix UAF in error path

Sam Page (sam4k) working with Trend Micro Zero Day Initiative reported
a UAF in the tipc_buf_append() error path:

BUG: KASAN: slab-use-after-free in kfree_skb_list_reason+0x47e/0x4c0
linux/net/core/skbuff.c:1183
Read of size 8 at addr ffff88804d2a7c80 by task poc/8034

CPU: 1 PID: 8034 Comm: poc Not tainted 6.8.2 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.16.0-debian-1.16.0-5 04/01/2014
Call Trace:
<IRQ>
__dump_stack linux/lib/dump_stack.c:88
dump_stack_lvl+0xd9/0x1b0 linux/lib/dump_stack.c:106
print_address_description linux/mm/kasan/report.c:377
print_report+0xc4/0x620 linux/mm/kasan/report.c:488
kasan_report+0xda/0x110 linux/mm/kasan/report.c:601
kfree_skb_list_reason+0x47e/0x4c0 linux/net/core/skbuff.c:1183
skb_release_data+0x5af/0x880 linux/net/core/skbuff.c:1026
skb_release_all linux/net/core/skbuff.c:1094
__kfree_skb linux/net/core/skbuff.c:1108
kfree_skb_reason+0x12d/0x210 linux/net/core/skbuff.c:1144
kfree_skb linux/./include/linux/skbuff.h:1244
tipc_buf_append+0x425/0xb50 linux/net/tipc/msg.c:186
tipc_link_input+0x224/0x7c0 linux/net/tipc/link.c:1324
tipc_link_rcv+0x76e/0x2d70 linux/net/tipc/link.c:1824
tipc_rcv+0x45f/0x10f0 linux/net/tipc/node.c:2159
tipc_udp_recv+0x73b/0x8f0 linux/net/tipc/udp_media.c:390
udp_queue_rcv_one_skb+0xad2/0x1850 linux/net/ipv4/udp.c:2108
udp_queue_rcv_skb+0x131/0xb00 linux/net/ipv4/udp.c:2186
udp_unicast_rcv_skb+0x165/0x3b0 linux/net/ipv4/udp.c:2346
__udp4_lib_rcv+0x2594/0x3400 linux/net/ipv4/udp.c:2422
ip_protocol_deliver_rcu+0x30c/0x4e0 linux/net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x2e4/0x520 linux/net/ipv4/ip_input.c:233
NF_HOOK linux/./include/linux/netfilter.h:314
NF_HOOK linux/./include/linux/netfilter.h:308
ip_local_deliver+0x18e/0x1f0 linux/net/ipv4/ip_input.c:254
dst_input linux/./include/net/dst.h:461
ip_rcv_finish linux/net/ipv4/ip_input.c:449
NF_HOOK linux/./include/linux/netfilter.h:314
NF_HOOK linux/./include/linux/netfilter.h:308
ip_rcv+0x2c5/0x5d0 linux/net/ipv4/ip_input.c:569
__netif_receive_skb_one_core+0x199/0x1e0 linux/net/core/dev.c:5534
__netif_receive_skb+0x1f/0x1c0 linux/net/core/dev.c:5648
process_backlog+0x101/0x6b0 linux/net/core/dev.c:5976
__napi_poll.constprop.0+0xba/0x550 linux/net/core/dev.c:6576
napi_poll linux/net/core/dev.c:6645
net_rx_action+0x95a/0xe90 linux/net/core/dev.c:6781
__do_softirq+0x21f/0x8e7 linux/kernel/softirq.c:553
do_softirq linux/kernel/softirq.c:454
do_softirq+0xb2/0xf0 linux/kernel/softirq.c:441
</IRQ>
<TASK>
__local_bh_enable_ip+0x100/0x120 linux/kernel/softirq.c:381
local_bh_enable linux/./include/linux/bottom_half.h:33
rcu_read_unlock_bh linux/./include/linux/rcupdate.h:851
__dev_queue_xmit+0x871/0x3ee0 linux/net/core/dev.c:4378
dev_queue_xmit linux/./include/linux/netdevice.h:3169
neigh_hh_output linux/./include/net/neighbour.h:526
neigh_output linux/./include/net/neighbour.h:540
ip_finish_output2+0x169f/0x2550 linux/net/ipv4/ip_output.c:235
__ip_finish_output linux/net/ipv4/ip_output.c:313
__ip_finish_output+0x49e/0x950 linux/net/ipv4/ip_output.c:295
ip_finish_output+0x31/0x310 linux/net/ipv4/ip_output.c:323
NF_HOOK_COND linux/./include/linux/netfilter.h:303
ip_output+0x13b/0x2a0 linux/net/ipv4/ip_output.c:433
dst_output linux/./include/net/dst.h:451
ip_local_out linux/net/ipv4/ip_output.c:129
ip_send_skb+0x3e5/0x560 linux/net/ipv4/ip_output.c:1492
udp_send_skb+0x73f/0x1530 linux/net/ipv4/udp.c:963
udp_sendmsg+0x1a36/0x2b40 linux/net/ipv4/udp.c:1250
inet_sendmsg+0x105/0x140 linux/net/ipv4/af_inet.c:850
sock_sendmsg_nosec linux/net/socket.c:730
__sock_sendmsg linux/net/socket.c:745
__sys_sendto+0x42c/0x4e0 linux/net/socket.c:2191
__do_sys_sendto linux/net/socket.c:2203
__se_sys_sendto linux/net/socket.c:2199
__x64_sys_sendto+0xe0/0x1c0 linux/net/socket.c:2199
do_syscall_x64 linux/arch/x86/entry/common.c:52
do_syscall_
---truncated---