CVE-2026-23277
Full vulnerability record from the local CVENow database.
Description
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
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-03-20 09:16:13.533000
Last modified
2026-11-05 22:18:11.010000
View original CVE JSON
{
"id": "CVE-2026-23277",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-03-20T09:16:13.533",
"lastModified": "2026-11-05T22:18:11.010",
"vulnStatus": "Modified",
"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->dev to the slave device\nbeforehand.\n\nWhen a gretap tunnel is a TEQL slave, the transmit path reaches\niptunnel_xmit() which saves dev = skb->dev (still pointing to teql0\nmaster) and later calls iptunnel_xmit_stats(dev, pkt_len). This\nfunction does:\n\n get_cpu_ptr(dev->tstats)\n\nSince teql_master_setup() does not set dev->pcpu_stat_type to\nNETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats\nfor teql0, so dev->tstats 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 <TASK>\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->dev = 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 desreferenciación de puntero NULL en iptunnel_xmit en la transmisión del esclavo TEQL\n\nteql_master_xmit() llama a netdev_start_xmit(skb, slave) para transmitir a través de dispositivos esclavos, pero no actualiza skb->dev al dispositivo esclavo de antemano.\n\nCuando un túnel gretap es un esclavo TEQL, la ruta de transmisión llega a iptunnel_xmit() que guarda dev = skb->dev (todavía apuntando al maestro teql0) y luego llama a iptunnel_xmit_stats(dev, pkt_len). Esta función hace:\n\n get_cpu_ptr(dev->tstats)\n\nDado que teql_master_setup() no establece dev->pcpu_stat_type en NETDEV_PCPU_STAT_TSTATS, la pila de red central nunca asigna tstats para teql0, por lo que dev->tstats es NULL. get_cpu_ptr(NULL) calcula NULL + __per_cpu_offset[cpu], lo que resulta en un fallo de página.\n\n ERROR: no se puede manejar el fallo de página para la dirección: ffff8880e6659018\n #PF: acceso de escritura de supervisor en modo kernel\n #PF: código_de_error(0x0002) - página 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->dev = slave antes de llamar a netdev_start_xmit(), para que las funciones de transmisión del túnel vean el dispositivo esclavo correcto con tstats correctamente asignados."
}
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