================================================================== BUG: KASAN: use-after-free in fib_flush+0x77/0x120 net/ipv4/fib_frontend.c:193 Read of size 8 at addr ffff888150088000 by task kworker/u4:3/302 CPU: 1 PID: 302 Comm: kworker/u4:3 Tainted: G W 5.10.238-syzkaller-00282-gd76d4cd0623a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: netns cleanup_net Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309 fib_flush+0x77/0x120 net/ipv4/fib_frontend.c:193 __remove_nexthop_fib+0xab/0x260 net/ipv4/nexthop.c:879 __remove_nexthop net/ipv4/nexthop.c:893 [inline] remove_nexthop+0x75/0x4d0 net/ipv4/nexthop.c:919 remove_nh_grp_entry net/ipv4/nexthop.c:797 [inline] remove_nexthop_from_groups+0x193/0xe40 net/ipv4/nexthop.c:846 __remove_nexthop net/ipv4/nexthop.c:904 [inline] remove_nexthop+0x38a/0x4d0 net/ipv4/nexthop.c:919 flush_all_nexthops net/ipv4/nexthop.c:1237 [inline] nexthop_net_exit+0x3a/0xa0 net/ipv4/nexthop.c:2012 ops_exit_list net/core/net_namespace.c:185 [inline] cleanup_net+0x586/0xb70 net/core/net_namespace.c:609 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Allocated by task 25963: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] ____kasan_kmalloc mm/kasan/common.c:509 [inline] __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518 kasan_kmalloc include/linux/kasan.h:254 [inline] kmem_cache_alloc_trace+0x184/0x2e0 mm/slub.c:2974 kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:664 [inline] ip_fib_net_init net/ipv4/fib_frontend.c:1547 [inline] fib_net_init+0xe0/0x2c0 net/ipv4/fib_frontend.c:1606 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:144 setup_net+0x36d/0xb50 net/core/net_namespace.c:345 copy_net_ns+0x314/0x520 net/core/net_namespace.c:486 create_new_namespaces+0x3a2/0x650 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231 ksys_unshare+0x4ac/0x7d0 kernel/fork.c:3156 __do_sys_unshare kernel/fork.c:3224 [inline] __se_sys_unshare kernel/fork.c:3222 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3222 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 302: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1595 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1621 slab_free mm/slub.c:3203 [inline] kfree+0xc0/0x270 mm/slub.c:4191 ip_fib_net_exit+0x32f/0x350 net/ipv4/fib_frontend.c:1595 fib_net_exit+0x6c/0x80 net/ipv4/fib_frontend.c:1629 ops_exit_list net/core/net_namespace.c:185 [inline] cleanup_net+0x586/0xb70 net/core/net_namespace.c:609 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 __call_rcu kernel/rcu/tree.c:2976 [inline] call_rcu+0x105/0x1040 kernel/rcu/tree.c:3050 netlink_release+0x1288/0x1690 net/netlink/af_netlink.c:796 __sock_release net/socket.c:597 [inline] sock_close+0xe0/0x270 net/socket.c:1286 __fput+0x2fb/0x770 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare kernel/entry/common.c:199 [inline] syscall_exit_to_user_mode+0x68/0x90 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb Second to last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 insert_work+0x52/0x310 kernel/workqueue.c:1352 __queue_work+0x923/0xca0 kernel/workqueue.c:1518 __queue_delayed_work+0x188/0x200 kernel/workqueue.c:1672 mod_delayed_work_on+0x7b/0xd0 kernel/workqueue.c:1746 mod_delayed_work include/linux/workqueue.h:545 [inline] wb_shutdown+0x164/0x1b0 mm/backing-dev.c:351 bdi_unregister+0x15e/0x4f0 mm/backing-dev.c:880 del_gendisk+0x479/0x9e0 block/genhd.c:929 loop_remove+0x46/0xb0 drivers/block/loop.c:2210 loop_control_ioctl+0x487/0x550 drivers/block/loop.c:2309 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb The buggy address belongs to the object at ffff888150088000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 0 bytes inside of 2048-byte region [ffff888150088000, ffff888150088800) The buggy address belongs to the page: page:ffffea0005402200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x150088 head:ffffea0005402200 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042d80 raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 12488, ts 516366691264, free_ts 508351038269 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5357 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1808 [inline] new_slab+0x84/0x3f0 mm/slub.c:1869 new_slab_objects mm/slub.c:2627 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2791 __slab_alloc+0x63/0xa0 mm/slub.c:2831 slab_alloc_node mm/slub.c:2913 [inline] slab_alloc mm/slub.c:2955 [inline] __kmalloc_track_caller+0x1ef/0x320 mm/slub.c:4536 __kmalloc_reserve net/core/skbuff.c:144 [inline] __alloc_skb+0xdc/0x520 net/core/skbuff.c:212 alloc_skb include/linux/skbuff.h:1126 [inline] nlmsg_new include/net/netlink.h:953 [inline] audit_buffer_alloc kernel/audit.c:1799 [inline] audit_log_start+0x3df/0x860 kernel/audit.c:1917 audit_seccomp+0x62/0x160 kernel/auditsc.c:2675 seccomp_log kernel/seccomp.c:1004 [inline] __seccomp_filter+0xb4c/0x1990 kernel/seccomp.c:1247 __secure_computing+0xea/0x290 kernel/seccomp.c:1313 syscall_trace_enter+0xb5/0x170 kernel/entry/common.c:58 __syscall_enter_from_user_work kernel/entry/common.c:81 [inline] syscall_enter_from_user_mode+0x20/0x30 kernel/entry/common.c:99 do_syscall_64+0x13/0x40 arch/x86/entry/common.c:41 entry_SYSCALL_64_after_hwframe+0x61/0xcb page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] __free_pages_ok+0x7fc/0x820 mm/page_alloc.c:1629 free_the_page mm/page_alloc.c:5418 [inline] __free_pages+0xdd/0x380 mm/page_alloc.c:5427 __free_slab+0xcf/0x190 mm/slub.c:1894 free_slab mm/slub.c:1909 [inline] discard_slab mm/slub.c:1915 [inline] unfreeze_partials+0x15f/0x190 mm/slub.c:2410 put_cpu_partial+0xc1/0x180 mm/slub.c:2446 __slab_free+0x2c9/0x3a0 mm/slub.c:3095 do_slab_free mm/slub.c:3191 [inline] ___cache_free+0x111/0x130 mm/slub.c:3210 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:583 slab_alloc_node mm/slub.c:2947 [inline] slab_alloc mm/slub.c:2955 [inline] kmem_cache_alloc+0x165/0x2e0 mm/slub.c:2960 getname_flags+0xb9/0x500 fs/namei.c:141 getname+0x19/0x20 fs/namei.c:212 do_sys_openat2+0xd9/0x6d0 fs/open.c:1211 Memory state around the buggy address: ffff888150087f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888150087f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888150088000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888150088080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888150088100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== general protection fault, probably for non-canonical address 0xfef7fc2840000025: 0000 [#1] PREEMPT SMP KASAN KASAN: maybe wild-memory-access in range [0xf7c0014200000128-0xf7c001420000012f] CPU: 0 PID: 302 Comm: kworker/u4:3 Tainted: G B W 5.10.238-syzkaller-00282-gd76d4cd0623a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: netns cleanup_net RIP: 0010:fib_flush+0x96/0x120 net/ipv4/fib_frontend.c:193 Code: 00 74 08 4c 89 e7 e8 99 1c c4 fd 4d 8b 3c 24 4d 85 ff 75 0f e8 2b 2c 8a fd eb 3b e8 24 2c 8a fd 4d 89 e7 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 6b 1c c4 fd 4d 8b 27 48 89 df 4c RSP: 0018:ffffc900079e79d0 EFLAGS: 00010a03 RAX: 1ef8002840000025 RBX: ffff888110812680 RCX: 0000000000000286 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888150088008 RBP: ffffc900079e7a10 R08: 0000000000000004 R09: 0000000000000003 R10: fffffbfff0d8e448 R11: 1ffffffff0d8e448 R12: ffff888150088008 R13: dffffc0000000000 R14: 0000000000000000 R15: f7c001420000012e FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f62838acf98 CR3: 0000000123feb000 CR4: 00000000003506b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __remove_nexthop_fib+0xab/0x260 net/ipv4/nexthop.c:879 __remove_nexthop net/ipv4/nexthop.c:893 [inline] remove_nexthop+0x75/0x4d0 net/ipv4/nexthop.c:919 remove_nh_grp_entry net/ipv4/nexthop.c:797 [inline] remove_nexthop_from_groups+0x193/0xe40 net/ipv4/nexthop.c:846 __remove_nexthop net/ipv4/nexthop.c:904 [inline] remove_nexthop+0x38a/0x4d0 net/ipv4/nexthop.c:919 flush_all_nexthops net/ipv4/nexthop.c:1237 [inline] nexthop_net_exit+0x3a/0xa0 net/ipv4/nexthop.c:2012 ops_exit_list net/core/net_namespace.c:185 [inline] cleanup_net+0x586/0xb70 net/core/net_namespace.c:609 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Modules linked in: ---[ end trace 90baa47f4bc1d019 ]--- RIP: 0010:fib_flush+0x96/0x120 net/ipv4/fib_frontend.c:193 Code: 00 74 08 4c 89 e7 e8 99 1c c4 fd 4d 8b 3c 24 4d 85 ff 75 0f e8 2b 2c 8a fd eb 3b e8 24 2c 8a fd 4d 89 e7 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 6b 1c c4 fd 4d 8b 27 48 89 df 4c RSP: 0018:ffffc900079e79d0 EFLAGS: 00010a03 RAX: 1ef8002840000025 RBX: ffff888110812680 RCX: 0000000000000286 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888150088008 RBP: ffffc900079e7a10 R08: 0000000000000004 R09: 0000000000000003 R10: fffffbfff0d8e448 R11: 1ffffffff0d8e448 R12: ffff888150088008 R13: dffffc0000000000 R14: 0000000000000000 R15: f7c001420000012e FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f62838acf98 CR3: 000000012a16e000 CR4: 00000000003506b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 00 74 08 4c add %dh,0x4c(%rax,%rcx,1) 4: 89 e7 mov %esp,%edi 6: e8 99 1c c4 fd call 0xfdc41ca4 b: 4d 8b 3c 24 mov (%r12),%r15 f: 4d 85 ff test %r15,%r15 12: 75 0f jne 0x23 14: e8 2b 2c 8a fd call 0xfd8a2c44 19: eb 3b jmp 0x56 1b: e8 24 2c 8a fd call 0xfd8a2c44 20: 4d 89 e7 mov %r12,%r15 23: 4c 89 f8 mov %r15,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 4c 89 ff mov %r15,%rdi 34: e8 6b 1c c4 fd call 0xfdc41ca4 39: 4d 8b 27 mov (%r15),%r12 3c: 48 89 df mov %rbx,%rdi 3f: 4c rex.WR