{"id":"CVE-2026-23004","summary":"dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ndst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()\n\nsyzbot was able to crash the kernel in rt6_uncached_list_flush_dev()\nin an interesting way [1]\n\nCrash happens in list_del_init()/INIT_LIST_HEAD() while writing\nlist-\u003eprev, while the prior write on list-\u003enext went well.\n\nstatic inline void INIT_LIST_HEAD(struct list_head *list)\n{\n\tWRITE_ONCE(list-\u003enext, list); // This went well\n\tWRITE_ONCE(list-\u003eprev, list); // Crash, @list has been freed.\n}\n\nIssue here is that rt6_uncached_list_del() did not attempt to lock\nul-\u003elock, as list_empty(&rt-\u003edst.rt_uncached) returned\ntrue because the WRITE_ONCE(list-\u003enext, list) happened on the other CPU.\n\nWe might use list_del_init_careful() and list_empty_careful(),\nor make sure rt6_uncached_list_del() always grabs the spinlock\nwhenever rt-\u003edst.rt_uncached_list has been set.\n\nA similar fix is neeed for IPv4.\n\n[1]\n\n BUG: KASAN: slab-use-after-free in INIT_LIST_HEAD include/linux/list.h:46 [inline]\n BUG: KASAN: slab-use-after-free in list_del_init include/linux/list.h:296 [inline]\n BUG: KASAN: slab-use-after-free in rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]\n BUG: KASAN: slab-use-after-free in rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020\nWrite of size 8 at addr ffff8880294cfa78 by task kworker/u8:14/3450\n\nCPU: 0 UID: 0 PID: 3450 Comm: kworker/u8:14 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)}\nTainted: [L]=SOFTLOCKUP\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025\nWorkqueue: netns cleanup_net\nCall Trace:\n \u003cTASK\u003e\n  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120\n  print_address_description mm/kasan/report.c:378 [inline]\n  print_report+0xca/0x240 mm/kasan/report.c:482\n  kasan_report+0x118/0x150 mm/kasan/report.c:595\n  INIT_LIST_HEAD include/linux/list.h:46 [inline]\n  list_del_init include/linux/list.h:296 [inline]\n  rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]\n  rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020\n  addrconf_ifdown+0x143/0x18a0 net/ipv6/addrconf.c:3853\n addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1\n  notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85\n  call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]\n  call_netdevice_notifiers net/core/dev.c:2282 [inline]\n  netif_close_many+0x29c/0x410 net/core/dev.c:1785\n  unregister_netdevice_many_notify+0xb50/0x2330 net/core/dev.c:12353\n  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]\n  ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248\n  cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696\n  process_one_work kernel/workqueue.c:3257 [inline]\n  process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n  worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n  kthread+0x711/0x8a0 kernel/kthread.c:463\n  ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n \u003c/TASK\u003e\n\nAllocated by task 803:\n  kasan_save_stack mm/kasan/common.c:57 [inline]\n  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78\n  unpoison_slab_object mm/kasan/common.c:340 [inline]\n  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366\n  kasan_slab_alloc include/linux/kasan.h:253 [inline]\n  slab_post_alloc_hook mm/slub.c:4953 [inline]\n  slab_alloc_node mm/slub.c:5263 [inline]\n  kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270\n  dst_alloc+0x105/0x170 net/core/dst.c:89\n  ip6_dst_alloc net/ipv6/route.c:342 [inline]\n  icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333\n  mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844\n  mld_send_cr net/ipv6/mcast.c:2154 [inline]\n  mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693\n  process_one_work kernel/workqueue.c:3257 [inline]\n  process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n  worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n  kthread+0x711/0x8a0 kernel/kthread.c:463\n  ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr\n---truncated---","modified":"2026-04-02T17:30:17.067342363Z","published":"2026-01-25T14:36:18.233Z","related":["CGA-fm45-7wxg-h5fh","SUSE-SU-2026:0928-1","SUSE-SU-2026:0961-1","SUSE-SU-2026:0962-1","SUSE-SU-2026:0984-1","SUSE-SU-2026:1003-1","SUSE-SU-2026:1041-1","SUSE-SU-2026:1077-1","SUSE-SU-2026:1078-1","SUSE-SU-2026:1081-1","SUSE-SU-2026:1131-1","SUSE-SU-2026:20667-1","SUSE-SU-2026:20720-1","SUSE-SU-2026:20838-1","SUSE-SU-2026:20845-1","SUSE-SU-2026:20876-1","SUSE-SU-2026:20931-1","openSUSE-SU-2026:20416-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23004.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/722de945216144af7cd4d39bdeb936108d2595a7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/815db2363e51f0ef416947492d4dac5b7a520f56"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a6f0c4d5796ab89b5a28a890ce542344d58bd69"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f24a52948c95e02facbca2b3b6eb5a225e27eb01"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23004.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23004"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"78df76a065ae3b5dbcb9a29912adc02f697de498"},{"fixed":"815db2363e51f0ef416947492d4dac5b7a520f56"},{"fixed":"f24a52948c95e02facbca2b3b6eb5a225e27eb01"},{"fixed":"722de945216144af7cd4d39bdeb936108d2595a7"},{"fixed":"9a6f0c4d5796ab89b5a28a890ce542344d58bd69"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23004.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.6.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.78"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23004.json"}}],"schema_version":"1.7.5"}