==================================================================
BUG: KASAN: slab-use-after-free in fib_rules_lookup+0x15e/0xeb0 net/core/fib_rules.c:321
Read of size 8 at addr ffff88804fe91280 by task dhcpcd/29660

CPU: 0 UID: 101 PID: 29660 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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]
 rcu_read_unlock_bh include/linux/rcupdate.h:912 [inline]
 __dev_queue_xmit+0x1ed7/0x37f0 net/core/dev.c:4907
 packet_snd net/packet/af_packet.c:3082 [inline]
 packet_sendmsg+0x3d95/0x5040 net/packet/af_packet.c:3114
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 sock_write_iter+0x498/0x4e0 net/socket.c:1255
 do_iter_readv_writev+0x612/0x8c0 fs/read_write.c:-1
 vfs_writev+0x343/0x990 fs/read_write.c:1059
 do_writev+0x154/0x2e0 fs/read_write.c:1105
 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
RIP: 0033:0x7f5e8083a407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fffd8feb620 EFLAGS: 00000202 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f5e807b0780 RCX: 00007f5e8083a407
RDX: 0000000000000002 RSI: 00007fffd8feb680 RDI: 0000000000000003
RBP: 000000000000005c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007fffd8feb6c0
R13: 000055c9ef758890 R14: 00007fffd8feb710 R15: 00007fffd8ffb8e0
 </TASK>

Allocated by task 17794:
 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 ffff88804fe91200
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 128 bytes inside of
 freed 192-byte region [ffff88804fe91200, ffff88804fe912c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88804fe91800 pfn:0x4fe91
flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000200 ffff88813fe163c0 ffffea00009a2190 ffffea00015ae710
raw: ffff88804fe91800 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 8797, tgid 8793 (syz.0.765), ts 200840779672, free_ts 194109943029
 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_ipportip6_resize+0xb30/0x1c60 net/netfilter/ipset/ip_set_hash_gen.h:710
 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 23 tgid 23 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
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
 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

Memory state around the buggy address:
 ffff88804fe91180: 00 00 00 00 00 00 00 03 fc fc fc fc fc fc fc fc
 ffff88804fe91200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88804fe91280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff88804fe91300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88804fe91380: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
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