CVE-2026-23277 (GCVE-0-2026-23277)

Vulnerability from cvelistv5 – Published: 2026-03-20 08:08 – Updated: 2026-03-20 08:08
VLAI?
Title
net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit teql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit through slave devices, but does not update skb->dev to the slave device beforehand. When a gretap tunnel is a TEQL slave, the transmit path reaches iptunnel_xmit() which saves dev = skb->dev (still pointing to teql0 master) and later calls iptunnel_xmit_stats(dev, pkt_len). This function does: get_cpu_ptr(dev->tstats) Since teql_master_setup() does not set dev->pcpu_stat_type to NETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats for teql0, so dev->tstats is NULL. get_cpu_ptr(NULL) computes NULL + __per_cpu_offset[cpu], resulting in a page fault. BUG: unable to handle page fault for address: ffff8880e6659018 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 68bc067 P4D 68bc067 PUD 0 Oops: Oops: 0002 [#1] SMP KASAN PTI RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89) Call Trace: <TASK> ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847) __gre_xmit (net/ipv4/ip_gre.c:478) gre_tap_xmit (net/ipv4/ip_gre.c:779) teql_master_xmit (net/sched/sch_teql.c:319) dev_hard_start_xmit (net/core/dev.c:3887) sch_direct_xmit (net/sched/sch_generic.c:347) __dev_queue_xmit (net/core/dev.c:4802) neigh_direct_output (net/core/neighbour.c:1660) ip_finish_output2 (net/ipv4/ip_output.c:237) __ip_finish_output.part.0 (net/ipv4/ip_output.c:315) ip_mc_output (net/ipv4/ip_output.c:369) ip_send_skb (net/ipv4/ip_output.c:1508) udp_send_skb (net/ipv4/udp.c:1195) udp_sendmsg (net/ipv4/udp.c:1485) inet_sendmsg (net/ipv4/af_inet.c:859) __sys_sendto (net/socket.c:2206) Fix this by setting skb->dev = slave before calling netdev_start_xmit(), so that tunnel xmit functions see the correct slave device with properly allocated tstats.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 039f50629b7f860f36644ed1f34b27da9aa62f43 , < 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4 (git)
Affected: 039f50629b7f860f36644ed1f34b27da9aa62f43 , < 21ea283c2750c8307aa35ee832b0951cc993c27d (git)
Affected: 039f50629b7f860f36644ed1f34b27da9aa62f43 , < 0cc0c2e661af418bbf7074179ea5cfffc0a5c466 (git)
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    Linux Linux Affected: 4.5
Unaffected: 0 , < 4.5 (semver)
Unaffected: 6.18.19 , ≤ 6.18.* (semver)
Unaffected: 6.19.9 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc4 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_teql.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0bad9c86edd22dec4df83c2b29872d66fd8a2ff4",
              "status": "affected",
              "version": "039f50629b7f860f36644ed1f34b27da9aa62f43",
              "versionType": "git"
            },
            {
              "lessThan": "21ea283c2750c8307aa35ee832b0951cc993c27d",
              "status": "affected",
              "version": "039f50629b7f860f36644ed1f34b27da9aa62f43",
              "versionType": "git"
            },
            {
              "lessThan": "0cc0c2e661af418bbf7074179ea5cfffc0a5c466",
              "status": "affected",
              "version": "039f50629b7f860f36644ed1f34b27da9aa62f43",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_teql.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.5"
            },
            {
              "lessThan": "4.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.19",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0-rc4",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit\n\nteql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit\nthrough slave devices, but does not update skb-\u003edev to the slave device\nbeforehand.\n\nWhen a gretap tunnel is a TEQL slave, the transmit path reaches\niptunnel_xmit() which saves dev = skb-\u003edev (still pointing to teql0\nmaster) and later calls iptunnel_xmit_stats(dev, pkt_len). This\nfunction does:\n\n    get_cpu_ptr(dev-\u003etstats)\n\nSince teql_master_setup() does not set dev-\u003epcpu_stat_type to\nNETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats\nfor teql0, so dev-\u003etstats is NULL. get_cpu_ptr(NULL) computes\nNULL + __per_cpu_offset[cpu], resulting in a page fault.\n\n BUG: unable to handle page fault for address: ffff8880e6659018\n #PF: supervisor write access in kernel mode\n #PF: error_code(0x0002) - not-present page\n PGD 68bc067 P4D 68bc067 PUD 0\n Oops: Oops: 0002 [#1] SMP KASAN PTI\n RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89)\n Call Trace:\n  \u003cTASK\u003e\n  ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)\n  __gre_xmit (net/ipv4/ip_gre.c:478)\n  gre_tap_xmit (net/ipv4/ip_gre.c:779)\n  teql_master_xmit (net/sched/sch_teql.c:319)\n  dev_hard_start_xmit (net/core/dev.c:3887)\n  sch_direct_xmit (net/sched/sch_generic.c:347)\n  __dev_queue_xmit (net/core/dev.c:4802)\n  neigh_direct_output (net/core/neighbour.c:1660)\n  ip_finish_output2 (net/ipv4/ip_output.c:237)\n  __ip_finish_output.part.0 (net/ipv4/ip_output.c:315)\n  ip_mc_output (net/ipv4/ip_output.c:369)\n  ip_send_skb (net/ipv4/ip_output.c:1508)\n  udp_send_skb (net/ipv4/udp.c:1195)\n  udp_sendmsg (net/ipv4/udp.c:1485)\n  inet_sendmsg (net/ipv4/af_inet.c:859)\n  __sys_sendto (net/socket.c:2206)\n\nFix this by setting skb-\u003edev = slave before calling\nnetdev_start_xmit(), so that tunnel xmit functions see the correct\nslave device with properly allocated tstats."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-20T08:08:57.394Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0bad9c86edd22dec4df83c2b29872d66fd8a2ff4"
        },
        {
          "url": "https://git.kernel.org/stable/c/21ea283c2750c8307aa35ee832b0951cc993c27d"
        },
        {
          "url": "https://git.kernel.org/stable/c/0cc0c2e661af418bbf7074179ea5cfffc0a5c466"
        }
      ],
      "title": "net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23277",
    "datePublished": "2026-03-20T08:08:57.394Z",
    "dateReserved": "2026-01-13T15:37:45.991Z",
    "dateUpdated": "2026-03-20T08:08:57.394Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23277\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-03-20T09:16:13.533\",\"lastModified\":\"2026-03-20T13:37:50.737\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit\\n\\nteql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit\\nthrough slave devices, but does not update skb-\u003edev to the slave device\\nbeforehand.\\n\\nWhen a gretap tunnel is a TEQL slave, the transmit path reaches\\niptunnel_xmit() which saves dev = skb-\u003edev (still pointing to teql0\\nmaster) and later calls iptunnel_xmit_stats(dev, pkt_len). This\\nfunction does:\\n\\n    get_cpu_ptr(dev-\u003etstats)\\n\\nSince teql_master_setup() does not set dev-\u003epcpu_stat_type to\\nNETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats\\nfor teql0, so dev-\u003etstats is NULL. get_cpu_ptr(NULL) computes\\nNULL + __per_cpu_offset[cpu], resulting in a page fault.\\n\\n BUG: unable to handle page fault for address: ffff8880e6659018\\n #PF: supervisor write access in kernel mode\\n #PF: error_code(0x0002) - not-present page\\n PGD 68bc067 P4D 68bc067 PUD 0\\n Oops: Oops: 0002 [#1] SMP KASAN PTI\\n RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89)\\n Call Trace:\\n  \u003cTASK\u003e\\n  ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)\\n  __gre_xmit (net/ipv4/ip_gre.c:478)\\n  gre_tap_xmit (net/ipv4/ip_gre.c:779)\\n  teql_master_xmit (net/sched/sch_teql.c:319)\\n  dev_hard_start_xmit (net/core/dev.c:3887)\\n  sch_direct_xmit (net/sched/sch_generic.c:347)\\n  __dev_queue_xmit (net/core/dev.c:4802)\\n  neigh_direct_output (net/core/neighbour.c:1660)\\n  ip_finish_output2 (net/ipv4/ip_output.c:237)\\n  __ip_finish_output.part.0 (net/ipv4/ip_output.c:315)\\n  ip_mc_output (net/ipv4/ip_output.c:369)\\n  ip_send_skb (net/ipv4/ip_output.c:1508)\\n  udp_send_skb (net/ipv4/udp.c:1195)\\n  udp_sendmsg (net/ipv4/udp.c:1485)\\n  inet_sendmsg (net/ipv4/af_inet.c:859)\\n  __sys_sendto (net/socket.c:2206)\\n\\nFix this by setting skb-\u003edev = slave before calling\\nnetdev_start_xmit(), so that tunnel xmit functions see the correct\\nslave device with properly allocated tstats.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\\n\\nnet/sched: teql: corrige la desreferenciaci\u00f3n de puntero NULL en iptunnel_xmit en la transmisi\u00f3n del esclavo TEQL\\n\\nteql_master_xmit() llama a netdev_start_xmit(skb, slave) para transmitir a trav\u00e9s de dispositivos esclavos, pero no actualiza skb-\u0026gt;dev al dispositivo esclavo de antemano.\\n\\nCuando un t\u00fanel gretap es un esclavo TEQL, la ruta de transmisi\u00f3n llega a iptunnel_xmit() que guarda dev = skb-\u0026gt;dev (todav\u00eda apuntando al maestro teql0) y luego llama a iptunnel_xmit_stats(dev, pkt_len). Esta funci\u00f3n hace:\\n\\n    get_cpu_ptr(dev-\u0026gt;tstats)\\n\\nDado que teql_master_setup() no establece dev-\u0026gt;pcpu_stat_type en NETDEV_PCPU_STAT_TSTATS, la pila de red central nunca asigna tstats para teql0, por lo que dev-\u0026gt;tstats es NULL. get_cpu_ptr(NULL) calcula NULL + __per_cpu_offset[cpu], lo que resulta en un fallo de p\u00e1gina.\\n\\n ERROR: no se puede manejar el fallo de p\u00e1gina para la direcci\u00f3n: ffff8880e6659018\\n #PF: acceso de escritura de supervisor en modo kernel\\n #PF: c\u00f3digo_de_error(0x0002) - p\u00e1gina no presente\\n PGD 68bc067 P4D 68bc067 PUD 0\\n Oops: Oops: 0002 [#1] SMP KASAN PTI\\n RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89)\\n Traza de Llamadas:\\n  \\n  ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)\\n  __gre_xmit (net/ipv4/ip_gre.c:478)\\n  gre_tap_xmit (net/ipv4/ip_gre.c:779)\\n  teql_master_xmit (net/sched/sch_teql.c:319)\\n  dev_hard_start_xmit (net/core/dev.c:3887)\\n  sch_direct_xmit (net/sched/sch_generic.c:347)\\n  __dev_queue_xmit (net/core/dev.c:4802)\\n  neigh_direct_output (net/core/neighbour.c:1660)\\n  ip_finish_output2 (net/ipv4/ip_output.c:237)\\n  __ip_finish_output.part.0 (net/ipv4/ip_output.c:315)\\n  ip_mc_output (net/ipv4/ip_output.c:369)\\n  ip_send_skb (net/ipv4/ip_output.c:1508)\\n  udp_send_skb (net/ipv4/udp.c:1195)\\n  udp_sendmsg (net/ipv4/udp.c:1485)\\n  inet_sendmsg (net/ipv4/af_inet.c:859)\\n  __sys_sendto (net/socket.c:2206)\\n\\nSolucione esto estableciendo skb-\u0026gt;dev = slave antes de llamar a netdev_start_xmit(), para que las funciones de transmisi\u00f3n del t\u00fanel vean el dispositivo esclavo correcto con tstats correctamente asignados.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0bad9c86edd22dec4df83c2b29872d66fd8a2ff4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/0cc0c2e661af418bbf7074179ea5cfffc0a5c466\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/21ea283c2750c8307aa35ee832b0951cc993c27d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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