CVE-2026-23277

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit<br /> <br /> teql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit<br /> through slave devices, but does not update skb-&gt;dev to the slave device<br /> beforehand.<br /> <br /> When a gretap tunnel is a TEQL slave, the transmit path reaches<br /> iptunnel_xmit() which saves dev = skb-&gt;dev (still pointing to teql0<br /> master) and later calls iptunnel_xmit_stats(dev, pkt_len). This<br /> function does:<br /> <br /> get_cpu_ptr(dev-&gt;tstats)<br /> <br /> Since teql_master_setup() does not set dev-&gt;pcpu_stat_type to<br /> NETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats<br /> for teql0, so dev-&gt;tstats is NULL. get_cpu_ptr(NULL) computes<br /> NULL + __per_cpu_offset[cpu], resulting in a page fault.<br /> <br /> BUG: unable to handle page fault for address: ffff8880e6659018<br /> #PF: supervisor write access in kernel mode<br /> #PF: error_code(0x0002) - not-present page<br /> PGD 68bc067 P4D 68bc067 PUD 0<br /> Oops: Oops: 0002 [#1] SMP KASAN PTI<br /> RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89)<br /> Call Trace:<br /> <br /> ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)<br /> __gre_xmit (net/ipv4/ip_gre.c:478)<br /> gre_tap_xmit (net/ipv4/ip_gre.c:779)<br /> teql_master_xmit (net/sched/sch_teql.c:319)<br /> dev_hard_start_xmit (net/core/dev.c:3887)<br /> sch_direct_xmit (net/sched/sch_generic.c:347)<br /> __dev_queue_xmit (net/core/dev.c:4802)<br /> neigh_direct_output (net/core/neighbour.c:1660)<br /> ip_finish_output2 (net/ipv4/ip_output.c:237)<br /> __ip_finish_output.part.0 (net/ipv4/ip_output.c:315)<br /> ip_mc_output (net/ipv4/ip_output.c:369)<br /> ip_send_skb (net/ipv4/ip_output.c:1508)<br /> udp_send_skb (net/ipv4/udp.c:1195)<br /> udp_sendmsg (net/ipv4/udp.c:1485)<br /> inet_sendmsg (net/ipv4/af_inet.c:859)<br /> __sys_sendto (net/socket.c:2206)<br /> <br /> Fix this by setting skb-&gt;dev = slave before calling<br /> netdev_start_xmit(), so that tunnel xmit functions see the correct<br /> slave device with properly allocated tstats.