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BUG: KASAN: slab-use-after-free in fib_rules_lookup+0x15e/0xeb0 net/core/fib_rules.c:321
Read of size 8 at addr ffff888063826d80 by task kworker/1:15/8908

CPU: 1 UID: 0 PID: 8908 Comm: kworker/1:15 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events_long defense_work_handler
Call Trace:
 <IRQ>
 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_input_slow net/ipv4/route.c:2353 [inline]
 ip_route_input_rcu+0x19ee/0x3190 net/ipv4/route.c:2540
 ip_route_input_noref+0x17c/0x270 net/ipv4/route.c:2551
 arp_process+0xaab/0x18c0 net/ipv4/arp.c:841
 NF_HOOK+0x33a/0x3c0 include/linux/netfilter.h:-1
 __netif_receive_skb_one_core net/core/dev.c:6204 [inline]
 __netif_receive_skb net/core/dev.c:6317 [inline]
 process_backlog+0xbf0/0x1860 net/core/dev.c:6668
 __napi_poll+0xaa/0x330 net/core/dev.c:7727
 napi_poll net/core/dev.c:7790 [inline]
 net_rx_action+0x61d/0xf50 net/core/dev.c:7947
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 do_softirq+0x76/0xd0 kernel/softirq.c:523
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 update_defense_level+0x867/0xcb0 net/netfilter/ipvs/ip_vs_ctl.c:210
 defense_work_handler+0x2d/0xd0 net/netfilter/ipvs/ip_vs_ctl.c:235
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478
 kthread+0x389/0x470 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 26268:
 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:5296 [inline]
 __kmalloc_node_track_caller_noprof+0x4d7/0x7b0 mm/slub.c:5408
 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:3242
 __do_sys_unshare kernel/fork.c:3316 [inline]
 __se_sys_unshare kernel/fork.c:3314 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3314
 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 23:
 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:2689 [inline]
 __rcu_free_sheaf_prepare+0x12d/0x2a0 mm/slub.c:2940
 rcu_free_sheaf+0x31/0x200 mm/slub.c:5850
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x78b/0x10a0 kernel/rcu/tree.c:2869
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x389/0x470 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 ffff888063826d00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 128 bytes inside of
 freed 192-byte region [ffff888063826d00, ffff888063826dc0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888063826500 pfn:0x63826
flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000200 ffff88813fe163c0 ffffea0001f4de10 ffffea0000aed5d0
raw: ffff888063826500 000000080010000f 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 16910, tgid 16908 (syz.3.3390), ts 433108323242, free_ts 428543357773
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x24ae/0x2530 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x336/0x3d0 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x320/0x720 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_noprof+0x464/0x750 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 hash_netportnet6_resize+0xcd3/0x1df0 net/netfilter/ipset/ip_set_hash_gen.h:728
 call_ad+0x439/0xb50 net/netfilter/ipset/ip_set_core.c:1758
 ip_set_ad+0x824/0x9d0 net/netfilter/ipset/ip_set_core.c:1842
 nfnetlink_rcv_msg+0xcc2/0x12b0 net/netfilter/nfnetlink.c:300
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 nfnetlink_rcv+0x2b9/0x28c0 net/netfilter/nfnetlink.c:667
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x9b9/0xa20 net/socket.c:2699
page last free pid 4998 tgid 4998 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 __slab_free+0x274/0x2c0 mm/slub.c:5613
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 __kmalloc_cache_noprof+0x2b6/0x660 mm/slub.c:5415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 kernfs_fop_open+0x3ac/0xce0 fs/kernfs/file.c:641
 do_dentry_open+0x816/0x1380 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x2e3b/0x3890 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 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

Memory state around the buggy address:
 ffff888063826c80: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff888063826d00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888063826d80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff888063826e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888063826e80: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc
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