{"cve":"CVE-2024-40905","nvd":{"published":"2024-07-12T13:15:13.847","modified":"2026-10-15T01:18:36.790","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix possible race in __fib6_drop_pcpu_from()\n\nsyzbot found a race in __fib6_drop_pcpu_from() [1]\n\nIf compiler reads more than once (*ppcpu_rt),\nsecond read could read NULL, if another cpu clears\nthe value in rt6_get_pcpu_route().\n\nAdd a READ_ONCE() to prevent this race.\n\nAlso add rcu_read_lock()/rcu_read_unlock() because\nwe rely on RCU protection while dereferencing pcpu_rt.\n\n[1]\n\nOops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] PREEMPT SMP KASAN PTI\nKASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]\nCPU: 0 PID: 7543 Comm: kworker/u8:17 Not tainted 6.10.0-rc1-syzkaller-00013-g2bfcfd584ff5 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024\nWorkqueue: netns cleanup_net\n RIP: 0010:__fib6_drop_pcpu_from.part.0+0x10a/0x370 net/ipv6/ip6_fib.c:984\nCode: f8 48 c1 e8 03 80 3c 28 00 0f 85 16 02 00 00 4d 8b 3f 4d 85 ff 74 31 e8 74 a7 fa f7 49 8d bf 90 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c 28 00 0f 85 1e 02 00 00 49 8b 87 90 00 00 00 48 8b 0c 24 48\nRSP: 0018:ffffc900040df070 EFLAGS: 00010206\nRAX: 0000000000000012 RBX: 0000000000000001 RCX: ffffffff89932e16\nRDX: ffff888049dd1e00 RSI: ffffffff89932d7c RDI: 0000000000000091\nRBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000007\nR10: 0000000000000001 R11: 0000000000000006 R12: ffff88807fa080b8\nR13: fffffbfff1a9a07d R14: ffffed100ff41022 R15: 0000000000000001\nFS:  0000000000000000(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000001b32c26000 CR3: 000000005d56e000 CR4: 00000000003526f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n  __fib6_drop_pcpu_from net/ipv6/ip6_fib.c:966 [inline]\n  fib6_drop_pcpu_from net/ipv6/ip6_fib.c:1027 [inline]\n  fib6_purge_rt+0x7f2/0x9f0 net/ipv6/ip6_fib.c:1038\n  fib6_del_route net/ipv6/ip6_fib.c:1998 [inline]\n  fib6_del+0xa70/0x17b0 net/ipv6/ip6_fib.c:2043\n  fib6_clean_node+0x426/0x5b0 net/ipv6/ip6_fib.c:2205\n  fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2127\n  fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2175\n  fib6_clean_tree+0xd7/0x120 net/ipv6/ip6_fib.c:2255\n  __fib6_clean_all+0x100/0x2d0 net/ipv6/ip6_fib.c:2271\n  rt6_sync_down_dev net/ipv6/route.c:4906 [inline]\n  rt6_disable_ip+0x7ed/0xa00 net/ipv6/route.c:4911\n  addrconf_ifdown.isra.0+0x117/0x1b40 net/ipv6/addrconf.c:3855\n  addrconf_notify+0x223/0x19e0 net/ipv6/addrconf.c:3778\n  notifier_call_chain+0xb9/0x410 kernel/notifier.c:93\n  call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:1992\n  call_netdevice_notifiers_extack net/core/dev.c:2030 [inline]\n  call_netdevice_notifiers net/core/dev.c:2044 [inline]\n  dev_close_many+0x333/0x6a0 net/core/dev.c:1585\n  unregister_netdevice_many_notify+0x46d/0x19f0 net/core/dev.c:11193\n  unregister_netdevice_many net/core/dev.c:11276 [inline]\n  default_device_exit_batch+0x85b/0xae0 net/core/dev.c:11759\n  ops_exit_list+0x128/0x180 net/core/net_namespace.c:178\n  cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:640\n  process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231\n  process_scheduled_works kernel/workqueue.c:3312 [inline]\n  worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393\n  kthread+0x2c1/0x3a0 kernel/kthread.c:389\n  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","score":4.7},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/09e5a5a80e205922151136069e440477d6816914","https://git.kernel.org/stable/c/2498960dac9b6fc49b6d1574f7cd1a4872744adf","https://git.kernel.org/stable/c/7e796c3fefa8b17b30e7252886ae8cffacd2b9ef","https://git.kernel.org/stable/c/a0bc020592b54a8f3fa2b7f244b6e39e526c2e12","https://git.kernel.org/stable/c/b01e1c030770ff3b4fe37fc7cc6bca03f594133f"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:52:42.518321223+00:00"},"epss":{"cve":"CVE-2024-40905","score":0.00272,"percentile":0.19426,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}