{"id":"CVE-2026-31517","state":"PUBLISHED","title":"xfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly\n\nIn iptfs_reassem_cont(), IP-TFS attempts to append data to the new inner\npacket 'newskb' that is being reassembled. First a zero-copy approach is\ntried if it succeeds then newskb becomes non-linear.\n\nWhen a subsequent fragment in the same datagram does not meet the\nfast-path conditions, a memory copy is performed. It calls skb_put() to\nappend the data and as newskb is non-linear it triggers\nSKB_LINEAR_ASSERT check.\n\n Oops: invalid opcode: 0000 [#1] SMP NOPTI\n [...]\n RIP: 0010:skb_put+0x3c/0x40\n [...]\n Call Trace:\n  <IRQ>\n  iptfs_reassem_cont+0x1ab/0x5e0 [xfrm_iptfs]\n  iptfs_input_ordered+0x2af/0x380 [xfrm_iptfs]\n  iptfs_input+0x122/0x3e0 [xfrm_iptfs]\n  xfrm_input+0x91e/0x1a50\n  xfrm4_esp_rcv+0x3a/0x110\n  ip_protocol_deliver_rcu+0x1d7/0x1f0\n  ip_local_deliver_finish+0xbe/0x1e0\n  __netif_receive_skb_core.constprop.0+0xb56/0x1120\n  __netif_receive_skb_list_core+0x133/0x2b0\n  netif_receive_skb_list_internal+0x1ff/0x3f0\n  napi_complete_done+0x81/0x220\n  virtnet_poll+0x9d6/0x116e [virtio_net]\n  __napi_poll.constprop.0+0x2b/0x270\n  net_rx_action+0x162/0x360\n  handle_softirqs+0xdc/0x510\n  __irq_exit_rcu+0xe7/0x110\n  irq_exit_rcu+0xe/0x20\n  common_interrupt+0x85/0xa0\n  </IRQ>\n  <TASK>\n\nFix this by checking if the skb is non-linear. If it is, linearize it by\ncalling skb_linearize(). As the initial allocation of newskb originally\nreserved enough tailroom for the entire reassembled packet we do not\nneed to check if we have enough tailroom or extend it.","publishedAt":"2026-04-22T13:54:33.522Z","updatedAt":"2026-05-11T22:10:19.646Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7","status":"affected","lessThan":"33a7b36268933c75bdc355e5531951e0ea9f1951","versionType":"git"},{"version":"5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7","status":"affected","lessThan":"7fdfe8f6efeb0e1200e22a903f2471539f54522b","versionType":"git"},{"version":"5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7","status":"affected","lessThan":"0b352f83cabfefdaafa806d6471f0eca117dc7d5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_iptfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.18.21","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.11","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_iptfs.c"]}],"references":["https://git.kernel.org/stable/c/33a7b36268933c75bdc355e5531951e0ea9f1951","https://git.kernel.org/stable/c/7fdfe8f6efeb0e1200e22a903f2471539f54522b","https://git.kernel.org/stable/c/0b352f83cabfefdaafa806d6471f0eca117dc7d5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31517.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31517","state":"PUBLISHED","datePublished":"2026-04-22T13:54:33.522Z","dateUpdated":"2026-05-11T22:10:19.646Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.108Z"},"containers":{"cna":{"title":"xfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly\n\nIn iptfs_reassem_cont(), IP-TFS attempts to append data to the new inner\npacket 'newskb' that is being reassembled. First a zero-copy approach is\ntried if it succeeds then newskb becomes non-linear.\n\nWhen a subsequent fragment in the same datagram does not meet the\nfast-path conditions, a memory copy is performed. It calls skb_put() to\nappend the data and as newskb is non-linear it triggers\nSKB_LINEAR_ASSERT check.\n\n Oops: invalid opcode: 0000 [#1] SMP NOPTI\n [...]\n RIP: 0010:skb_put+0x3c/0x40\n [...]\n Call Trace:\n  <IRQ>\n  iptfs_reassem_cont+0x1ab/0x5e0 [xfrm_iptfs]\n  iptfs_input_ordered+0x2af/0x380 [xfrm_iptfs]\n  iptfs_input+0x122/0x3e0 [xfrm_iptfs]\n  xfrm_input+0x91e/0x1a50\n  xfrm4_esp_rcv+0x3a/0x110\n  ip_protocol_deliver_rcu+0x1d7/0x1f0\n  ip_local_deliver_finish+0xbe/0x1e0\n  __netif_receive_skb_core.constprop.0+0xb56/0x1120\n  __netif_receive_skb_list_core+0x133/0x2b0\n  netif_receive_skb_list_internal+0x1ff/0x3f0\n  napi_complete_done+0x81/0x220\n  virtnet_poll+0x9d6/0x116e [virtio_net]\n  __napi_poll.constprop.0+0x2b/0x270\n  net_rx_action+0x162/0x360\n  handle_softirqs+0xdc/0x510\n  __irq_exit_rcu+0xe7/0x110\n  irq_exit_rcu+0xe/0x20\n  common_interrupt+0x85/0xa0\n  </IRQ>\n  <TASK>\n\nFix this by checking if the skb is non-linear. If it is, linearize it by\ncalling skb_linearize(). As the initial allocation of newskb originally\nreserved enough tailroom for the entire reassembled packet we do not\nneed to check if we have enough tailroom or extend it."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7","status":"affected","lessThan":"33a7b36268933c75bdc355e5531951e0ea9f1951","versionType":"git"},{"version":"5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7","status":"affected","lessThan":"7fdfe8f6efeb0e1200e22a903f2471539f54522b","versionType":"git"},{"version":"5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7","status":"affected","lessThan":"0b352f83cabfefdaafa806d6471f0eca117dc7d5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_iptfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.18.21","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.11","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_iptfs.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/33a7b36268933c75bdc355e5531951e0ea9f1951"},{"url":"https://git.kernel.org/stable/c/7fdfe8f6efeb0e1200e22a903f2471539f54522b"},{"url":"https://git.kernel.org/stable/c/0b352f83cabfefdaafa806d6471f0eca117dc7d5"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:10:19.646Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.18.21"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.19.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}