==================================================================
BUG: KASAN: slab-use-after-free in fib_rules_lookup+0x15e/0xeb0 net/core/fib_rules.c:321
Read of size 8 at addr ffff888020715480 by task kworker/u8:17/8235

CPU: 1 UID: 0 PID: 8235 Comm: kworker/u8:17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 fib_rules_lookup+0x15e/0xeb0 net/core/fib_rules.c:321
 __fib_lookup+0x106/0x210 net/ipv4/fib_rules.c:96
 ip_route_output_key_hash_rcu+0x294/0x2720 net/ipv4/route.c:2811
 ip_route_output_key_hash+0x18d/0x2a0 net/ipv4/route.c:2702
 __ip_route_output_key include/net/route.h:169 [inline]
 ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2929
 ip4_datagram_release_cb+0x89d/0xbe0 net/ipv4/datagram.c:118
 release_sock+0x233/0x290 net/core/sock.c:3861
 inet_shutdown+0x2b1/0x390 net/ipv4/af_inet.c:950
 udp_tunnel_sock_release+0x6d/0x80 net/ipv4/udp_tunnel_core.c:197
 fou_release net/ipv4/fou_core.c:562 [inline]
 fou_exit_net+0x17d/0x1f0 net/ipv4/fou_core.c:1230
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x43d/0x8d0 net/core/net_namespace.c:252
 cleanup_net+0x575/0x810 net/core/net_namespace.c:702
 process_one_work+0x93a/0x12b0 kernel/workqueue.c:3326
 process_scheduled_works kernel/workqueue.c:3409 [inline]
 worker_thread+0xb05/0x10d0 kernel/workqueue.c:3490
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 12637:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5360 [inline]
 __kmalloc_node_track_caller_noprof+0x57f/0x7c0 mm/slub.c:5495
 kmemdup_noprof+0x2b/0x70 mm/util.c:138
 kmemdup_noprof include/linux/fortify-string.h:763 [inline]
 fib_rules_register+0x2f/0x400 net/core/fib_rules.c:170
 fib4_rules_init+0x21/0x160 net/ipv4/fib_rules.c:508
 ip_fib_net_init net/ipv4/fib_frontend.c:1578 [inline]
 fib_net_init+0x17a/0x3e0 net/ipv4/fib_frontend.c:1628
 ops_init+0x35d/0x5d0 net/core/net_namespace.c:137
 setup_net+0x118/0x350 net/core/net_namespace.c:446
 copy_net_ns+0x4f9/0x720 net/core/net_namespace.c:579
 create_new_namespaces+0x3f0/0x6b0 kernel/nsproxy.c:132
 unshare_nsproxy_namespaces+0x149/0x190 kernel/nsproxy.c:234
 ksys_unshare+0x57d/0xa00 kernel/fork.c:3267
 __do_sys_unshare kernel/fork.c:3341 [inline]
 __se_sys_unshare kernel/fork.c:3339 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3339
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 7773:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2703 [inline]
 slab_free_freelist_hook mm/slub.c:2732 [inline]
 slab_free_bulk mm/slub.c:6437 [inline]
 kmem_cache_free_bulk+0x309/0x1260 mm/slub.c:7174
 kfree_bulk include/linux/slab.h:891 [inline]
 kvfree_rcu_bulk+0xc6/0x190 mm/slab_common.c:1502
 kfree_rcu_work+0xe8/0x160 mm/slab_common.c:1580
 process_one_work+0x93a/0x12b0 kernel/workqueue.c:3326
 process_scheduled_works kernel/workqueue.c:3409 [inline]
 worker_thread+0xb05/0x10d0 kernel/workqueue.c:3490
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 kvfree_call_rcu+0x90/0x3c0 mm/slab_common.c:1970
 ops_exit_rtnl_list net/core/net_namespace.c:181 [inline]
 ops_undo_list+0x319/0x8d0 net/core/net_namespace.c:248
 cleanup_net+0x575/0x810 net/core/net_namespace.c:702
 process_one_work+0x93a/0x12b0 kernel/workqueue.c:3326
 process_scheduled_works kernel/workqueue.c:3409 [inline]
 worker_thread+0xb05/0x10d0 kernel/workqueue.c:3490
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888020715400
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 128 bytes inside of
 freed 192-byte region [ffff888020715400, ffff8880207154c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888020715c00 pfn:0x20715
flags: 0x80000000000200(workingset|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000200 ffff88813fe1f3c0 ffffea0000a7fc10 ffffea00009b93d0
raw: ffff888020715c00 000000080010000d 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 4547086663, free_ts 4546605341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x2639/0x26b0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3406
 new_slab mm/slub.c:3452 [inline]
 refill_objects+0x2d8/0x350 mm/slub.c:7336
 refill_sheaf mm/slub.c:2830 [inline]
 __pcs_replace_empty_main+0x330/0x690 mm/slub.c:4701
 alloc_from_pcs mm/slub.c:4799 [inline]
 slab_alloc_node mm/slub.c:4931 [inline]
 __kmalloc_cache_noprof+0x468/0x6b0 mm/slub.c:5509
 _kmalloc_noprof include/linux/slab.h:969 [inline]
 _kzalloc_noprof include/linux/slab.h:1290 [inline]
 call_usermodehelper_setup+0x8e/0x270 kernel/umh.c:362
 kobject_uevent_env+0x665/0x9e0 lib/kobject_uevent.c:631
 driver_register+0x2d4/0x320 drivers/base/driver.c:182
 do_one_initcall+0x250/0x870 init/main.c:1347
 do_initcall_level+0x10a/0x1a0 init/main.c:1409
 do_initcalls+0x59/0xa0 init/main.c:1425
 kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
 kernel_init+0x1d/0x1d0 init/main.c:1548
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
page last free pid 69 tgid 69 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x10de/0x11c0 mm/page_alloc.c:2950
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
 __kasan_populate_vmalloc+0x1a8/0x1c0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd1a/0x1420 mm/vmalloc.c:2123
 __get_vm_area_node+0x1f2/0x300 mm/vmalloc.c:3226
 __vmalloc_node_range_noprof+0x358/0x1730 mm/vmalloc.c:4042
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4143
 alloc_thread_stack_node kernel/fork.c:359 [inline]
 dup_task_struct+0x28e/0x850 kernel/fork.c:929
 copy_process+0x81b/0x42e0 kernel/fork.c:2110
 kernel_clone+0x2d7/0x940 kernel/fork.c:2746
 user_mode_thread+0x110/0x180 kernel/fork.c:2822
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work+0x93a/0x12b0 kernel/workqueue.c:3326
 process_scheduled_works kernel/workqueue.c:3409 [inline]
 worker_thread+0xb05/0x10d0 kernel/workqueue.c:3490
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888020715380: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888020715400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888020715480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff888020715500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888020715580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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