GHSA-V66F-JQGM-8687
Vulnerability from github – Published: 2026-03-20 09:32 – Updated: 2026-07-14 15:31In 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: 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.
{
"affected": [],
"aliases": [
"CVE-2026-23277"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-20T09:16:13Z",
"severity": "MODERATE"
},
"details": "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.",
"id": "GHSA-v66f-jqgm-8687",
"modified": "2026-07-14T15:31:40Z",
"published": "2026-03-20T09:32:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23277"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0bad9c86edd22dec4df83c2b29872d66fd8a2ff4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0cc0c2e661af418bbf7074179ea5cfffc0a5c466"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/21ea283c2750c8307aa35ee832b0951cc993c27d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/383493b9940e3d1b5517424081b3e072e20ec43c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/57c153249143333bbf4ecf927bdf8aa2696ee397"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/59b06d8b9bdb6b64b3c534c18da68bce5ccd31be"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b1f563d670162e188a0f2aec39c24b67b106e17"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/81a43e8005366f16e629d8c95dfe05beaa8d36a7"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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