{"id":"CVE-2026-97612","summary":"net: mpls: clear inner_protocol when the last label is popped","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mpls: clear inner_protocol when the last label is popped\n\nskb_mpls_push() records the pre-encapsulation network header once, gated\non !skb-\u003einner_protocol. skb_mpls_pop() never clears that record, so it\noutlives the encapsulation it describes.\n\nOpen vSwitch can then re-push MPLS onto a packet whose\ninner_network_header still points at the older, deeper offset: push a\nlabel, pop every label, recirculate (ovs_flow_key_update() re-derives\nkey-\u003eeth.type and resets network_header, but leaves inner_*), then push\nagain. ovs_fragment() trusts the record:\n\n\tskb-\u003enetwork_header = skb-\u003einner_network_header;\n\nso skb_network_offset() goes negative. The bound check is signed:\n\n\tif (skb_network_offset(skb) \u003e MAX_L2_LEN)\n\na negative offset passes it, and prepare_frag() widens the value:\n\n\tunsigned int hlen = skb_network_offset(skb);\n\tmemcpy(&data-\u003el2_data, skb-\u003edata, hlen);\n\nwhich is a ~4GiB memcpy out of a 30-byte per-CPU buffer.\n\nReproduced on v7.3-rc1. RDX is the truncated length, (unsigned int)(-8):\n\n  BUG: unable to handle page fault for address: ffffe8ffffc16000\n  #PF: supervisor write access in kernel mode\n  Oops: 0002 [#1] SMP KASAN NOPTI\n  RIP: 0010:memcpy+0x8/0x20\n  RDX: 00000000fffffff8 RSI: ffff888105d732db RDI: ffffe8ffffc16000\n   prepare_frag+0x3df/0x4e0\n   ovs_fragment+0x589/0x7e0\n   do_output+0x4ce/0x5e0\n   do_execute_actions+0x55d2/0x7b30\n   ovs_execute_actions+0xea/0x450\n\nSame root-cause shape as commit 975b5b067f52 (\"ipv6: sr: restore network\nheader before routing and forwarding\"): a stale network header offset\nreaching a consumer that widens it. Here it originates in the MPLS\npush/pop path.\n\nClear inner_protocol once the packet is no longer MPLS, so a later push\nre-records the current header. net/sched/act_mpls.c is the only other\nskb_mpls_pop() caller and gets the same fix; sch_frag.c saves and\nrestores inner_protocol around fragmentation in the same way OVS does.","modified":"2026-09-26T03:48:27.910614861Z","published":"2026-09-25T10:22:21.423Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97612.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/011e17b5cae19b9f6a150923275e41c278de64f0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/78a86d75a70e1e227711c72865c59b1422d0a5ae"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b39120523475d6b436be7f6cb27d48064148a327"},{"type":"WEB","url":"https://git.kernel.org/stable/c/da8c3a7f5d3137fec4ff60a6248f5f6d66b6a63e"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97612.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97612"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"48d2ab609b6bbecb7698487c8579bc40de9d6dfa"},{"fixed":"011e17b5cae19b9f6a150923275e41c278de64f0"},{"fixed":"da8c3a7f5d3137fec4ff60a6248f5f6d66b6a63e"},{"fixed":"b39120523475d6b436be7f6cb27d48064148a327"},{"fixed":"78a86d75a70e1e227711c72865c59b1422d0a5ae"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97612.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.9.0"},{"fixed":"6.12.111"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97612.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}