{"api_version":"1","generated_at":"2026-08-24T07:17:01+00:00","cve":"CVE-2024-36933","urls":{"html":"https://cve.report/CVE-2024-36933","api":"https://cve.report/api/cve/CVE-2024-36933.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2024-36933","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2024-36933"},"summary":{"title":"nsh: Restore skb->{protocol,data,mac_header} for outer header in nsh_gso_segment().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnsh: Restore skb->{protocol,data,mac_header} for outer header in nsh_gso_segment().\n\nsyzbot triggered various splats (see [0] and links) by a crafted GSO\npacket of VIRTIO_NET_HDR_GSO_UDP layering the following protocols:\n\n  ETH_P_8021AD + ETH_P_NSH + ETH_P_IPV6 + IPPROTO_UDP\n\nNSH can encapsulate IPv4, IPv6, Ethernet, NSH, and MPLS.  As the inner\nprotocol can be Ethernet, NSH GSO handler, nsh_gso_segment(), calls\nskb_mac_gso_segment() to invoke inner protocol GSO handlers.\n\nnsh_gso_segment() does the following for the original skb before\ncalling skb_mac_gso_segment()\n\n  1. reset skb->network_header\n  2. save the original skb->{mac_heaeder,mac_len} in a local variable\n  3. pull the NSH header\n  4. resets skb->mac_header\n  5. set up skb->mac_len and skb->protocol for the inner protocol.\n\nand does the following for the segmented skb\n\n  6. set ntohs(ETH_P_NSH) to skb->protocol\n  7. push the NSH header\n  8. restore skb->mac_header\n  9. set skb->mac_header + mac_len to skb->network_header\n 10. restore skb->mac_len\n\nThere are two problems in 6-7 and 8-9.\n\n  (a)\n  After 6 & 7, skb->data points to the NSH header, so the outer header\n  (ETH_P_8021AD in this case) is stripped when skb is sent out of netdev.\n\n  Also, if NSH is encapsulated by NSH + Ethernet (so NSH-Ethernet-NSH),\n  skb_pull() in the first nsh_gso_segment() will make skb->data point\n  to the middle of the outer NSH or Ethernet header because the Ethernet\n  header is not pulled by the second nsh_gso_segment().\n\n  (b)\n  While restoring skb->{mac_header,network_header} in 8 & 9,\n  nsh_gso_segment() does not assume that the data in the linear\n  buffer is shifted.\n\n  However, udp6_ufo_fragment() could shift the data and change\n  skb->mac_header accordingly as demonstrated by syzbot.\n\n  If this happens, even the restored skb->mac_header points to\n  the middle of the outer header.\n\nIt seems nsh_gso_segment() has never worked with outer headers so far.\n\nAt the end of nsh_gso_segment(), the outer header must be restored for\nthe segmented skb, instead of the NSH header.\n\nTo do that, let's calculate the outer header position relatively from\nthe inner header and set skb->{data,mac_header,protocol} properly.\n\n[0]:\nBUG: KMSAN: uninit-value in ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:524 [inline]\nBUG: KMSAN: uninit-value in ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]\nBUG: KMSAN: uninit-value in ipvlan_queue_xmit+0xf44/0x16b0 drivers/net/ipvlan/ipvlan_core.c:668\n ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:524 [inline]\n ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]\n ipvlan_queue_xmit+0xf44/0x16b0 drivers/net/ipvlan/ipvlan_core.c:668\n ipvlan_start_xmit+0x5c/0x1a0 drivers/net/ipvlan/ipvlan_main.c:222\n __netdev_start_xmit include/linux/netdevice.h:4989 [inline]\n netdev_start_xmit include/linux/netdevice.h:5003 [inline]\n xmit_one net/core/dev.c:3547 [inline]\n dev_hard_start_xmit+0x244/0xa10 net/core/dev.c:3563\n __dev_queue_xmit+0x33ed/0x51c0 net/core/dev.c:4351\n dev_queue_xmit include/linux/netdevice.h:3171 [inline]\n packet_xmit+0x9c/0x6b0 net/packet/af_packet.c:276\n packet_snd net/packet/af_packet.c:3081 [inline]\n packet_sendmsg+0x8aef/0x9f10 net/packet/af_packet.c:3113\n sock_sendmsg_nosec net/socket.c:730 [inline]\n __sock_sendmsg net/socket.c:745 [inline]\n __sys_sendto+0x735/0xa10 net/socket.c:2191\n __do_sys_sendto net/socket.c:2203 [inline]\n __se_sys_sendto net/socket.c:2199 [inline]\n __x64_sys_sendto+0x125/0x1c0 net/socket.c:2199\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nUninit was created at:\n slab_post_alloc_hook mm/slub.c:3819 [inline]\n slab_alloc_node mm/slub.c:3860 [inline]\n __do_kmalloc_node mm/slub.c:3980 [inline]\n __kmalloc_node_track_caller+0x705/0x1000 mm/slub.c:4001\n kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:582\n __\n---truncated---","state":"PUBLISHED","assigner":"Linux","published_at":"2024-05-30 16:15:16","updated_at":"2026-08-04 11:18:32"},"problem_types":["CWE-908"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"5.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/29a07f2ee4d273760c2acbfc756e29eccd82470a","name":"https://git.kernel.org/stable/c/29a07f2ee4d273760c2acbfc756e29eccd82470a","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/46134031c20fd313d03b90169d64b2e05ca6b65c","name":"https://git.kernel.org/stable/c/46134031c20fd313d03b90169d64b2e05ca6b65c","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bbccf0caef2fa917d6d0692385a06ce3c262a216","name":"https://git.kernel.org/stable/c/bbccf0caef2fa917d6d0692385a06ce3c262a216","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5a4603fbc285752d19e4b415466db18ef3617e4a","name":"https://git.kernel.org/stable/c/5a4603fbc285752d19e4b415466db18ef3617e4a","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://lists.debian.org/debian-lts-announce/2024/06/msg00019.html","name":"https://lists.debian.org/debian-lts-announce/2024/06/msg00019.html","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Third 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original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2024","cve_id":"36933","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2024-36933","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2024-06-04T15:40:25.095830Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2024-06-04T17:47:53.616Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP 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Program 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the Linux kernel, the following vulnerability has been resolved:\n\nnsh: Restore skb->{protocol,data,mac_header} for outer header in nsh_gso_segment().\n\nsyzbot triggered various splats (see [0] and links) by a crafted GSO\npacket of VIRTIO_NET_HDR_GSO_UDP layering the following protocols:\n\n  ETH_P_8021AD + ETH_P_NSH + ETH_P_IPV6 + IPPROTO_UDP\n\nNSH can encapsulate IPv4, IPv6, Ethernet, NSH, and MPLS.  As the inner\nprotocol can be Ethernet, NSH GSO handler, nsh_gso_segment(), calls\nskb_mac_gso_segment() to invoke inner protocol GSO handlers.\n\nnsh_gso_segment() does the following for the original skb before\ncalling skb_mac_gso_segment()\n\n  1. reset skb->network_header\n  2. save the original skb->{mac_heaeder,mac_len} in a local variable\n  3. pull the NSH header\n  4. resets skb->mac_header\n  5. set up skb->mac_len and skb->protocol for the inner protocol.\n\nand does the following for the segmented skb\n\n  6. set ntohs(ETH_P_NSH) to skb->protocol\n  7. push the NSH header\n  8. restore skb->mac_header\n  9. set skb->mac_header + mac_len to skb->network_header\n 10. restore skb->mac_len\n\nThere are two problems in 6-7 and 8-9.\n\n  (a)\n  After 6 & 7, skb->data points to the NSH header, so the outer header\n  (ETH_P_8021AD in this case) is stripped when skb is sent out of netdev.\n\n  Also, if NSH is encapsulated by NSH + Ethernet (so NSH-Ethernet-NSH),\n  skb_pull() in the first nsh_gso_segment() will make skb->data point\n  to the middle of the outer NSH or Ethernet header because the Ethernet\n  header is not pulled by the second nsh_gso_segment().\n\n  (b)\n  While restoring skb->{mac_header,network_header} in 8 & 9,\n  nsh_gso_segment() does not assume that the data in the linear\n  buffer is shifted.\n\n  However, udp6_ufo_fragment() could shift the data and change\n  skb->mac_header accordingly as demonstrated by syzbot.\n\n  If this happens, even the restored skb->mac_header points to\n  the middle of the outer header.\n\nIt seems nsh_gso_segment() has never worked with outer headers so far.\n\nAt the end of nsh_gso_segment(), the outer header must be restored for\nthe segmented skb, instead of the NSH header.\n\nTo do that, let's calculate the outer header position relatively from\nthe inner header and set skb->{data,mac_header,protocol} properly.\n\n[0]:\nBUG: KMSAN: uninit-value in ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:524 [inline]\nBUG: KMSAN: uninit-value in ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]\nBUG: KMSAN: uninit-value in ipvlan_queue_xmit+0xf44/0x16b0 drivers/net/ipvlan/ipvlan_core.c:668\n ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:524 [inline]\n ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]\n ipvlan_queue_xmit+0xf44/0x16b0 drivers/net/ipvlan/ipvlan_core.c:668\n ipvlan_start_xmit+0x5c/0x1a0 drivers/net/ipvlan/ipvlan_main.c:222\n __netdev_start_xmit include/linux/netdevice.h:4989 [inline]\n netdev_start_xmit include/linux/netdevice.h:5003 [inline]\n xmit_one net/core/dev.c:3547 [inline]\n dev_hard_start_xmit+0x244/0xa10 net/core/dev.c:3563\n __dev_queue_xmit+0x33ed/0x51c0 net/core/dev.c:4351\n dev_queue_xmit include/linux/netdevice.h:3171 [inline]\n packet_xmit+0x9c/0x6b0 net/packet/af_packet.c:276\n packet_snd net/packet/af_packet.c:3081 [inline]\n packet_sendmsg+0x8aef/0x9f10 net/packet/af_packet.c:3113\n sock_sendmsg_nosec net/socket.c:730 [inline]\n __sock_sendmsg net/socket.c:745 [inline]\n __sys_sendto+0x735/0xa10 net/socket.c:2191\n __do_sys_sendto net/socket.c:2203 [inline]\n __se_sys_sendto net/socket.c:2199 [inline]\n __x64_sys_sendto+0x125/0x1c0 net/socket.c:2199\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nUninit was created at:\n slab_post_alloc_hook mm/slub.c:3819 [inline]\n slab_alloc_node mm/slub.c:3860 [inline]\n __do_kmalloc_node mm/slub.c:3980 [inline]\n __kmalloc_node_track_caller+0x705/0x1000 mm/slub.c:4001\n kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:582\n __\n---truncated---"}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-08-04T09:25:18.865Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a7c2c3c1caabcb4a3d6c47284c397507aaf54fe9"},{"url":"https://git.kernel.org/stable/c/46134031c20fd313d03b90169d64b2e05ca6b65c"},{"url":"https://git.kernel.org/stable/c/bbccf0caef2fa917d6d0692385a06ce3c262a216"},{"url":"https://git.kernel.org/stable/c/5a4603fbc285752d19e4b415466db18ef3617e4a"},{"url":"https://git.kernel.org/stable/c/37ed6f244ec5bda2e90b085084e322ea55d0aaa2"},{"url":"https://git.kernel.org/stable/c/696d18bb59727a2e0526c0802a812620be1c9340"},{"url":"https://git.kernel.org/stable/c/29a07f2ee4d273760c2acbfc756e29eccd82470a"},{"url":"https://git.kernel.org/stable/c/4b911a9690d72641879ea6d13cce1de31d346d79"}],"title":"nsh: Restore skb->{protocol,data,mac_header} for outer header in nsh_gso_segment().","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2024-36933","datePublished":"2024-05-30T15:29:23.764Z","dateReserved":"2024-05-30T15:25:07.071Z","dateUpdated":"2026-08-04T09:25:18.865Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2024-05-30 16:15:16","lastModifiedDate":"2026-08-04 11:18:32","problem_types":["CWE-908"],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9},{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2024-06-04T15:40:25.095830Z","id":"CVE-2024-36933","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"4.19.314","matchCriteriaId":"C5E3C473-9230-4E04-BD05-2D9CF39E9FC2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.4.276","matchCriteriaId":"126C6EEC-8874-4233-AE09-634924FCDDF4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.217","matchCriteriaId":"AC67C71C-2044-40BA-B590-61E562F69F89"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.159","matchCriteriaId":"F16678CD-F7C6-4BF6-ABA8-E7600857197B"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.91","matchCriteriaId":"4F8C886C-75AA-469B-A6A9-12BF1A29C0D5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.31","matchCriteriaId":"CDDB1F69-36AC-41C1-9192-E7CCEF5FFC00"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.8.10","matchCriteriaId":"6A6B920C-8D8F-4130-86B4-AD334F4CF2E3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc1:*:*:*:*:*:*","matchCriteriaId":"22BEDD49-2C6D-402D-9DBF-6646F6ECD10B"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc2:*:*:*:*:*:*","matchCriteriaId":"DF73CB2A-DFFD-46FB-9BFE-AA394F27EA37"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc3:*:*:*:*:*:*","matchCriteriaId":"52048DDA-FC5A-4363-95A0-A6357B4D7F8C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc4:*:*:*:*:*:*","matchCriteriaId":"A06B2CCF-3F43-4FA9-8773-C83C3F5764B2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc5:*:*:*:*:*:*","matchCriteriaId":"F850DCEC-E08B-4317-A33B-D2DCF39F601B"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc6:*:*:*:*:*:*","matchCriteriaId":"91326417-E981-482E-A5A3-28BC1327521B"}]}]},{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*","matchCriteriaId":"07B237A9-69A3-4A9C-9DA0-4E06BD37AE73"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2024","CveId":"36933","Ordinal":"1","Title":"nsh: Restore skb->{protocol,data,mac_header} for outer header in","CVE":"CVE-2024-36933","Year":"2024"},"notes":[{"CveYear":"2024","CveId":"36933","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnsh: Restore skb->{protocol,data,mac_header} for outer header in nsh_gso_segment().\n\nsyzbot triggered various splats (see [0] and links) by a crafted GSO\npacket of VIRTIO_NET_HDR_GSO_UDP layering the following protocols:\n\n  ETH_P_8021AD + ETH_P_NSH + ETH_P_IPV6 + IPPROTO_UDP\n\nNSH can encapsulate IPv4, IPv6, Ethernet, NSH, and MPLS.  As the inner\nprotocol can be Ethernet, NSH GSO handler, nsh_gso_segment(), calls\nskb_mac_gso_segment() to invoke inner protocol GSO handlers.\n\nnsh_gso_segment() does the following for the original skb before\ncalling skb_mac_gso_segment()\n\n  1. reset skb->network_header\n  2. save the original skb->{mac_heaeder,mac_len} in a local variable\n  3. pull the NSH header\n  4. resets skb->mac_header\n  5. set up skb->mac_len and skb->protocol for the inner protocol.\n\nand does the following for the segmented skb\n\n  6. set ntohs(ETH_P_NSH) to skb->protocol\n  7. push the NSH header\n  8. restore skb->mac_header\n  9. set skb->mac_header + mac_len to skb->network_header\n 10. restore skb->mac_len\n\nThere are two problems in 6-7 and 8-9.\n\n  (a)\n  After 6 & 7, skb->data points to the NSH header, so the outer header\n  (ETH_P_8021AD in this case) is stripped when skb is sent out of netdev.\n\n  Also, if NSH is encapsulated by NSH + Ethernet (so NSH-Ethernet-NSH),\n  skb_pull() in the first nsh_gso_segment() will make skb->data point\n  to the middle of the outer NSH or Ethernet header because the Ethernet\n  header is not pulled by the second nsh_gso_segment().\n\n  (b)\n  While restoring skb->{mac_header,network_header} in 8 & 9,\n  nsh_gso_segment() does not assume that the data in the linear\n  buffer is shifted.\n\n  However, udp6_ufo_fragment() could shift the data and change\n  skb->mac_header accordingly as demonstrated by syzbot.\n\n  If this happens, even the restored skb->mac_header points to\n  the middle of the outer header.\n\nIt seems nsh_gso_segment() has never worked with outer headers so far.\n\nAt the end of nsh_gso_segment(), the outer header must be restored for\nthe segmented skb, instead of the NSH header.\n\nTo do that, let's calculate the outer header position relatively from\nthe inner header and set skb->{data,mac_header,protocol} properly.\n\n[0]:\nBUG: KMSAN: uninit-value in ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:524 [inline]\nBUG: KMSAN: uninit-value in ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]\nBUG: KMSAN: uninit-value in ipvlan_queue_xmit+0xf44/0x16b0 drivers/net/ipvlan/ipvlan_core.c:668\n ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:524 [inline]\n ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]\n ipvlan_queue_xmit+0xf44/0x16b0 drivers/net/ipvlan/ipvlan_core.c:668\n ipvlan_start_xmit+0x5c/0x1a0 drivers/net/ipvlan/ipvlan_main.c:222\n __netdev_start_xmit include/linux/netdevice.h:4989 [inline]\n netdev_start_xmit include/linux/netdevice.h:5003 [inline]\n xmit_one net/core/dev.c:3547 [inline]\n dev_hard_start_xmit+0x244/0xa10 net/core/dev.c:3563\n __dev_queue_xmit+0x33ed/0x51c0 net/core/dev.c:4351\n dev_queue_xmit include/linux/netdevice.h:3171 [inline]\n packet_xmit+0x9c/0x6b0 net/packet/af_packet.c:276\n packet_snd net/packet/af_packet.c:3081 [inline]\n packet_sendmsg+0x8aef/0x9f10 net/packet/af_packet.c:3113\n sock_sendmsg_nosec net/socket.c:730 [inline]\n __sock_sendmsg net/socket.c:745 [inline]\n __sys_sendto+0x735/0xa10 net/socket.c:2191\n __do_sys_sendto net/socket.c:2203 [inline]\n __se_sys_sendto net/socket.c:2199 [inline]\n __x64_sys_sendto+0x125/0x1c0 net/socket.c:2199\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nUninit was created at:\n slab_post_alloc_hook mm/slub.c:3819 [inline]\n slab_alloc_node mm/slub.c:3860 [inline]\n __do_kmalloc_node mm/slub.c:3980 [inline]\n __kmalloc_node_track_caller+0x705/0x1000 mm/slub.c:4001\n kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:582\n __\n---truncated---","Type":"Description","Title":"nsh: Restore skb->{protocol,data,mac_header} for outer header in"}]}}}