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.
En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta: net/sched: teql: corrige la desreferenciación de puntero NULL en iptunnel_xmit en la transmisión del esclavo TEQL teql_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. Cuando 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: get_cpu_ptr(dev->tstats) Dado 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. ERROR: no se puede manejar el fallo de página para la dirección: ffff8880e6659018 #PF: acceso de escritura de supervisor en modo kernel #PF: código_de_error(0x0002) - página no presente 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) Traza de Llamadas: 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) Solucione 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.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | NONE |
| Integrity Impact | NONE |
| Availability Impact | HIGH |
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-476
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bfc2a6a80> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bfc2a7040> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde165880> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc6a4840> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bfc2a7a40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bfc2a4bc0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde1658c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bde167880> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bde165d00> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bfc2a6dc0> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* |