{"cve":"CVE-2024-56636","nvd":{"published":"2024-12-27T15:15:23.320","modified":"2026-06-17T08:12:36.650","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ngeneve: do not assume mac header is set in geneve_xmit_skb()\n\nWe should not assume mac header is set in output path.\n\nUse skb_eth_hdr() instead of eth_hdr() to fix the issue.\n\nsysbot reported the following :\n\n WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 skb_mac_header include/linux/skbuff.h:3052 [inline]\n WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 eth_hdr include/linux/if_ether.h:24 [inline]\n WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 geneve_xmit_skb drivers/net/geneve.c:898 [inline]\n WARNING: CPU: 0 PID: 11635 at include/linux/skbuff.h:3052 geneve_xmit+0x4c38/0x5730 drivers/net/geneve.c:1039\nModules linked in:\nCPU: 0 UID: 0 PID: 11635 Comm: syz.4.1423 Not tainted 6.12.0-syzkaller-10296-gaaf20f870da0 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\n RIP: 0010:skb_mac_header include/linux/skbuff.h:3052 [inline]\n RIP: 0010:eth_hdr include/linux/if_ether.h:24 [inline]\n RIP: 0010:geneve_xmit_skb drivers/net/geneve.c:898 [inline]\n RIP: 0010:geneve_xmit+0x4c38/0x5730 drivers/net/geneve.c:1039\nCode: 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\nRSP: 0018:ffffc90003b2f870 EFLAGS: 00010283\nRAX: 000000000000037a RBX: 000000000000ffff RCX: ffffc9000dc3d000\nRDX: 0000000000080000 RSI: ffffffff86428417 RDI: 0000000000000003\nRBP: ffffc90003b2f9f0 R08: 0000000000000003 R09: 000000000000ffff\nR10: 000000000000ffff R11: 0000000000000002 R12: ffff88806603c000\nR13: 0000000000000000 R14: ffff8880685b2780 R15: 0000000000000e23\nFS:  00007fdc2deed6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000001b30a1dff8 CR3: 0000000056b8c000 CR4: 00000000003526f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n  __netdev_start_xmit include/linux/netdevice.h:5002 [inline]\n  netdev_start_xmit include/linux/netdevice.h:5011 [inline]\n  __dev_direct_xmit+0x58a/0x720 net/core/dev.c:4490\n  dev_direct_xmit include/linux/netdevice.h:3181 [inline]\n  packet_xmit+0x1e4/0x360 net/packet/af_packet.c:285\n  packet_snd net/packet/af_packet.c:3146 [inline]\n  packet_sendmsg+0x2700/0x5660 net/packet/af_packet.c:3178\n  sock_sendmsg_nosec net/socket.c:711 [inline]\n  __sock_sendmsg net/socket.c:726 [inline]\n  __sys_sendto+0x488/0x4f0 net/socket.c:2197\n  __do_sys_sendto net/socket.c:2204 [inline]\n  __se_sys_sendto net/socket.c:2200 [inline]\n  __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2200\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x77/0x7f","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/177b72ed7c77b11e46dd4336d73a87a77a5603af","https://git.kernel.org/stable/c/2ee7bdc7cb40abfe658a71fbd10c7db2f4fc4f9a","https://git.kernel.org/stable/c/8588c99c7d47448fcae39e3227d6e2bb97aad86d","https://git.kernel.org/stable/c/97ce3a4ec55eac6b5e2949ffb04028d604afda3b","https://git.kernel.org/stable/c/b65958284401016b983078c68f70b047537f4aba"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:57:56.913276502+00:00"},"epss":{"cve":"CVE-2024-56636","score":0.00268,"percentile":0.18992,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}