CVE-2024-36886 tipc: fix UAF in error path

What is CVE-2024-36886?

CVE-2024-36886 is a critical use after free vulnerability in Debian Debian Linux, published on 30 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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---

Weakness: CWE-416

Which versions are affected by CVE-2024-36886?

It affects 2 products.

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2024-36886?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2024-36886 being exploited?

There is no known exploitation of CVE-2024-36886 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

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All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• How this page is made

Also known as BELL-CVE-2024-36886, DEBIAN-CVE-2024-36886, RHSA-2024:4547, RHSA-2024:4548, RHSA-2024:4713, UBUNTU-CVE-2024-36886.