---
id: CVE-2024-56636
title: 'geneve: do not assume mac header is set in geneve_xmit_skb()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  geneve: do not assume mac header is set in geneve_xmit_skb()

  We should not assume mac header is set in output path.

  Use skb_eth_hdr() instead of eth_hdr() to fix the …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b <
    d9fa09ca004befe9cf826d6820439cb6f93cecd7
  - >-
    Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b <
    b65958284401016b983078c68f70b047537f4aba
  - >-
    Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b <
    2ee7bdc7cb40abfe658a71fbd10c7db2f4fc4f9a
  - >-
    Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b <
    97ce3a4ec55eac6b5e2949ffb04028d604afda3b
  - >-
    Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b <
    177b72ed7c77b11e46dd4336d73a87a77a5603af
  - >-
    Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b <
    8588c99c7d47448fcae39e3227d6e2bb97aad86d
  - Linux 5.0
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T20:29:27.955958Z'
published: '2024-12-27'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T20:31:25.382Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2024-56636'
references:
  - url: 'https://git.kernel.org/stable/c/d9fa09ca004befe9cf826d6820439cb6f93cecd7'
  - url: 'https://git.kernel.org/stable/c/b65958284401016b983078c68f70b047537f4aba'
  - url: 'https://git.kernel.org/stable/c/2ee7bdc7cb40abfe658a71fbd10c7db2f4fc4f9a'
  - url: 'https://git.kernel.org/stable/c/97ce3a4ec55eac6b5e2949ffb04028d604afda3b'
  - url: 'https://git.kernel.org/stable/c/177b72ed7c77b11e46dd4336d73a87a77a5603af'
  - url: 'https://git.kernel.org/stable/c/8588c99c7d47448fcae39e3227d6e2bb97aad86d'
tags:
  - cve.org
epss: 0.00268
epssPercentile: 0.19057
ingestedAt: '2026-11-05T22:38:31.835Z'
---

## Overview

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

geneve: do not assume mac header is set in geneve_xmit_skb()

We should not assume mac header is set in output path.

Use skb_eth_hdr() instead of eth_hdr() to fix the issue.

sysbot reported the following :

 WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 skb_mac_header include/linux/skbuff.h:3052 [inline]
 WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 eth_hdr include/linux/if_ether.h:24 [inline]
 WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 geneve_xmit_skb drivers/net/geneve.c:898 [inline]
 WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 geneve_xmit+0x4c38/0x5730 drivers/net/geneve.c:1039
Modules linked in:
CPU: 0 UID: 0 PID: 11635 Comm: syz.4.1423 Not tainted 6.12.0-syzkaller-10296-gaaf20f870da0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
 RIP: 0010:skb_mac_header include/linux/skbuff.h:3052 [inline]
 RIP: 0010:eth_hdr include/linux/if_ether.h:24 [inline]
 RIP: 0010:geneve_xmit_skb drivers/net/geneve.c:898 [inline]
 RIP: 0010:geneve_xmit+0x4c38/0x5730 drivers/net/geneve.c:1039
Code: 21 c6 02 e9 35 d4 ff ff e8 a5 48 4c fb 90 0f 0b 90 e9 fd f5 ff ff e8 97 48 4c fb 90 0f 0b 90 e9 d8 f5 ff ff e8 89 48 4c fb 90 <0f> 0b 90 e9 41 e4 ff ff e8 7b 48 4c fb 90 0f 0b 90 e9 cd e7 ff ff
RSP: 0018:ffffc90003b2f870 EFLAGS: 00010283
RAX: 000000000000037a RBX: 000000000000ffff RCX: ffffc9000dc3d000
RDX: 0000000000080000 RSI: ffffffff86428417 RDI: 0000000000000003
RBP: ffffc90003b2f9f0 R08: 0000000000000003 R09: 000000000000ffff
R10: 000000000000ffff R11: 0000000000000002 R12: ffff88806603c000
R13: 0000000000000000 R14: ffff8880685b2780 R15: 0000000000000e23
FS:  00007fdc2deed6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30a1dff8 CR3: 0000000056b8c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
  __netdev_start_xmit include/linux/netdevice.h:5002 [inline]
  netdev_start_xmit include/linux/netdevice.h:5011 [inline]
  __dev_direct_xmit+0x58a/0x720 net/core/dev.c:4490
  dev_direct_xmit include/linux/netdevice.h:3181 [inline]
  packet_xmit+0x1e4/0x360 net/packet/af_packet.c:285
  packet_snd net/packet/af_packet.c:3146 [inline]
  packet_sendmsg+0x2700/0x5660 net/packet/af_packet.c:3178
  sock_sendmsg_nosec net/socket.c:711 [inline]
  __sock_sendmsg net/socket.c:726 [inline]
  __sys_sendto+0x488/0x4f0 net/socket.c:2197
  __do_sys_sendto net/socket.c:2204 [inline]
  __se_sys_sendto net/socket.c:2200 [inline]
  __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2200
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

## Affected

- `Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b < d9fa09ca004befe9cf826d6820439cb6f93cecd7`
- `Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b < b65958284401016b983078c68f70b047537f4aba`
- `Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b < 2ee7bdc7cb40abfe658a71fbd10c7db2f4fc4f9a`
- `Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b < 97ce3a4ec55eac6b5e2949ffb04028d604afda3b`
- `Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b < 177b72ed7c77b11e46dd4336d73a87a77a5603af`
- `Linux >= a025fb5f49ad38cf749753b16fcd031d0d678f2b < 8588c99c7d47448fcae39e3227d6e2bb97aad86d`
- `Linux 5.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.