{"id":"CVE-2026-98369","published":"2026-10-06T09:18:31.280","lastModified":"2026-10-07T07:17:11.410","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()\n\nsyzbot reported a suspicious RCU usage warning in ip6_pkt_drop():\n\n  WARNING: suspicious RCU usage in ip6_pkt_drop\n  include/net/addrconf.h:389 suspicious rcu_dereference_check() usage!\n\n  Call Trace:\n   __in6_dev_get_safely include/net/addrconf.h:389 [inline]\n   ip6_pkt_drop+0x596/0x610 net/ipv6/route.c:4620\n   ip6_pkt_discard+0x1c/0x30 net/ipv6/route.c:4651\n   xfrm_trans_reinject+0x324/0x630 net/xfrm/xfrm_input.c:806\n   process_one_work kernel/workqueue.c:3322 [inline]\n   process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405\n   worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486\n\nWhen commit 4f4920669d21 (\"xfrm: Reinject transport-mode packets through\nworkqueue\") converted xfrm_trans_reinject from a tasklet to a workqueue,\nthe reinjection loop ceased running in softirq context. Workqueue workers\nrun in process context where local_bh_disable() does not enter an RCU\nread-side critical section under CONFIG_PREEMPT_RCU.\n\nBecause finish callbacks (such as ip6_rcv_finish) expect to run under an\nRCU read lock (performing route lookups, l3mdev lookups, and accessing\nRCU-protected data structures), invoking them in workqueue context without\nrcu_read_lock() triggers RCU lockdep warnings.\n\nFurthermore, packets queued to the workqueue via xfrm_trans_queue_net()\nmay carry non-refcounted (noref) dst entries (e.g. from ip_route_input_noref).\nAdditionally, on netdevice unregistration, dst_dev_put() replaces dst->dev\nwith blackhole_netdev, so dst entries do not keep skb->dev alive while\nqueued in the workqueue.\n\nFix these issues by:\n1. Calling skb_dst_force(skb) in xfrm_trans_queue_net() while still in the\n   caller's RCU section to ensure dst is reference-counted before queuing.\n2. Holding a reference on skb->dev via dev_hold()/dev_put() across workqueue\n   deferral so skb->dev remains valid during finish() callback processing.\n3. Acquiring rcu_read_lock() around the finish callback invocation loop in\n   xfrm_trans_reinject().","cvssScore":7.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/0cda8273265d30cac6423834fd7d4acb75f04fdb","tags":[]},{"url":"https://git.kernel.org/stable/c/41e47f1664be86c91326f0afe0504a1162d00907","tags":[]},{"url":"https://git.kernel.org/stable/c/6601d91a85761f33351c71e04ec0bbd294ca07ce","tags":[]},{"url":"https://git.kernel.org/stable/c/664fc0941df7c1918b2cd4de6ee00469ba77d8e4","tags":[]},{"url":"https://git.kernel.org/stable/c/68a317b4aec8ca1868a39d69e40f9e29baa4f40a","tags":[]},{"url":"https://git.kernel.org/stable/c/6eb3b071be8e260543c604550c54dac66e6b174b","tags":[]},{"url":"https://git.kernel.org/stable/c/d2f5082f9e84653fa1a9e8aebaaff23e688f5e19","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"The Linux kernel's XFRM subsystem has a missing RCU read lock and reference counting in the xfrm_trans_reinject() function, causing potential data races and RCU lockdep warnings when reinjecting transport-mode packets through workqueue context. This can lead to system instability and incorrect packet handling.","exploitability":"Exploitation is difficult with no public exploit available and requires specific kernel configuration and packet processing conditions, but could potentially lead to privilege escalation or denial of service.","blast_radius":"The vulnerability affects systems using XFRM transport mode packet reinjection, particularly those with IPv6 routing and security policies, potentially causing widespread network disruption and system instability.","remediation":"Apply the kernel patch that adds missing rcu_read_lock(), skb_dst_force(), and dev_hold() calls to xfrm_trans_reinject() function in the Linux kernel.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["kernel","network","xfrm"],"model":"garnet-coder","analyzedAt":"2026-10-14T09:02:00.033Z"}}