{"id":"CVE-2026-98369","state":"PUBLISHED","title":"xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()","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().","publishedAt":"2026-10-06T08:46:54.188Z","updatedAt":"2026-10-19T09:18:21.221Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7d98b26684cb2390729525b341ea099f0badbe18","status":"affected","lessThan":"41e47f1664be86c91326f0afe0504a1162d00907","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"6601d91a85761f33351c71e04ec0bbd294ca07ce","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"0cda8273265d30cac6423834fd7d4acb75f04fdb","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"68a317b4aec8ca1868a39d69e40f9e29baa4f40a","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"6eb3b071be8e260543c604550c54dac66e6b174b","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"664fc0941df7c1918b2cd4de6ee00469ba77d8e4","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"d2f5082f9e84653fa1a9e8aebaaff23e688f5e19","versionType":"git"},{"version":"f520075da484306bbb8425afd2c42404ba74816f","status":"affected","versionType":"git"},{"version":"130d9e5017ade1b81d16783563edb38c12a2eab7","status":"affected","versionType":"git"},{"version":"5.15.75","status":"affected","lessThan":"5.15.222","versionType":"semver"},{"version":"5.19.17","status":"affected","lessThan":"5.20","versionType":"semver"},{"version":"6.0.3","status":"affected","lessThan":"6.1","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_input.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.1","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.54","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.8","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_input.c"]}],"references":["https://git.kernel.org/stable/c/41e47f1664be86c91326f0afe0504a1162d00907","https://git.kernel.org/stable/c/6601d91a85761f33351c71e04ec0bbd294ca07ce","https://git.kernel.org/stable/c/0cda8273265d30cac6423834fd7d4acb75f04fdb","https://git.kernel.org/stable/c/68a317b4aec8ca1868a39d69e40f9e29baa4f40a","https://git.kernel.org/stable/c/6eb3b071be8e260543c604550c54dac66e6b174b","https://git.kernel.org/stable/c/664fc0941df7c1918b2cd4de6ee00469ba77d8e4","https://git.kernel.org/stable/c/d2f5082f9e84653fa1a9e8aebaaff23e688f5e19"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98369.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98369","state":"PUBLISHED","datePublished":"2026-10-06T08:46:54.188Z","dateUpdated":"2026-10-19T09:18:21.221Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.344Z"},"containers":{"cna":{"title":"xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()","descriptions":[{"lang":"en","value":"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()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7d98b26684cb2390729525b341ea099f0badbe18","status":"affected","lessThan":"41e47f1664be86c91326f0afe0504a1162d00907","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"6601d91a85761f33351c71e04ec0bbd294ca07ce","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"0cda8273265d30cac6423834fd7d4acb75f04fdb","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"68a317b4aec8ca1868a39d69e40f9e29baa4f40a","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"6eb3b071be8e260543c604550c54dac66e6b174b","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"664fc0941df7c1918b2cd4de6ee00469ba77d8e4","versionType":"git"},{"version":"4f4920669d21e1060b7243e5118dc3b71ced1276","status":"affected","lessThan":"d2f5082f9e84653fa1a9e8aebaaff23e688f5e19","versionType":"git"},{"version":"f520075da484306bbb8425afd2c42404ba74816f","status":"affected","versionType":"git"},{"version":"130d9e5017ade1b81d16783563edb38c12a2eab7","status":"affected","versionType":"git"},{"version":"5.15.75","status":"affected","lessThan":"5.15.222","versionType":"semver"},{"version":"5.19.17","status":"affected","lessThan":"5.20","versionType":"semver"},{"version":"6.0.3","status":"affected","lessThan":"6.1","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_input.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.1","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.54","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.8","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_input.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/41e47f1664be86c91326f0afe0504a1162d00907"},{"url":"https://git.kernel.org/stable/c/6601d91a85761f33351c71e04ec0bbd294ca07ce"},{"url":"https://git.kernel.org/stable/c/0cda8273265d30cac6423834fd7d4acb75f04fdb"},{"url":"https://git.kernel.org/stable/c/68a317b4aec8ca1868a39d69e40f9e29baa4f40a"},{"url":"https://git.kernel.org/stable/c/6eb3b071be8e260543c604550c54dac66e6b174b"},{"url":"https://git.kernel.org/stable/c/664fc0941df7c1918b2cd4de6ee00469ba77d8e4"},{"url":"https://git.kernel.org/stable/c/d2f5082f9e84653fa1a9e8aebaaff23e688f5e19"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The use-after-free happens only when a queued packet's net_device or noref dst is freed before xfrm_trans_reinject() runs. A remote ESP peer sends the packet but cannot unregister the device or change routes, so the attacker who controls the whole race is local: they create the netns, veth and XFRM SA through xfrm_user netlink.\nAC:L - The attacker does both sides of the race. They send ESP transport-mode packets that xfrm4_transport_finish/xfrm6_transport_finish queue through xfrm_trans_queue(), then delete the veth or route while the workqueue is still behind. Flooding the queue up to max_backlog widens the window.\nPR:L - xfrm_user_rcv_msg checks netlink_net_capable(CAP_NET_ADMIN), which an unprivileged user gets in a new user and network namespace (unshare -Urn). That lets them create the SA, the veth devices and the routes the trigger needs.\nUI:N - No victim action is needed. The attacker sets up the namespace, sends the packets and tears down the device or route themselves.\nS:U - The freed net_device, dst_entry and RCU-protected route data are kernel memory, and the impact stays within the kernel's own security authority.\nC:H - ip6_rcv_finish and dst_input in xfrm_trans_reinject() read a freed skb->dev or noref dst_entry with no reference and no RCU lock. If an attacker reclaims that memory, these use-after-free reads can leak kernel memory.\nI:H - The freed dst_entry holds an input function pointer that dst_input() calls, and net_device is full of ops pointers. Reclaiming either object with attacker-controlled data gives a path to hijacking control flow.\nA:H - A use-after-free of the net_device or dst in the xfrm_trans_reinject worker crashes the kernel, and syzbot hit the missing-RCU path in ip6_pkt_drop. The attacker can trigger it repeatedly."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:18:21.221Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.75","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.18.54"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.2.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}