==================================================================
BUG: KASAN: slab-use-after-free in macvlan_forward_source+0x5d8/0x700 drivers/net/macvlan.c:442
Read of size 2 at addr ffff88805711cdfc by task kworker/u8:6/153

CPU: 1 UID: 0 PID: 153 Comm: kworker/u8:6 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound macvlan_process_broadcast
Call Trace:
 <IRQ>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 macvlan_forward_source+0x5d8/0x700 drivers/net/macvlan.c:442
 macvlan_handle_frame+0x2e2/0x12e0 drivers/net/macvlan.c:477
 __netif_receive_skb_core+0x95f/0x2f90 net/core/dev.c:6038
 __netif_receive_skb_one_core net/core/dev.c:6149 [inline]
 __netif_receive_skb+0x72/0x380 net/core/dev.c:6264
 process_backlog+0x54f/0x1340 net/core/dev.c:6616
 __napi_poll+0xae/0x320 net/core/dev.c:7680
 napi_poll net/core/dev.c:7743 [inline]
 net_rx_action+0x64a/0xe00 net/core/dev.c:7895
 handle_softirqs+0x22b/0x7c0 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]
 netif_rx+0x83/0x90 net/core/dev.c:5717
 macvlan_broadcast+0x373/0x630 drivers/net/macvlan.c:292
 macvlan_multicast_rx drivers/net/macvlan.c:-1 [inline]
 macvlan_process_broadcast+0x457/0x660 drivers/net/macvlan.c:340
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Allocated by task 13139:
 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]
 __kmalloc_cache_noprof+0x3e2/0x700 mm/slub.c:5776
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 snmp6_alloc_dev net/ipv6/addrconf.c:362 [inline]
 ipv6_add_dev+0x6aa/0x13a0 net/ipv6/addrconf.c:413
 addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3650
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2280 [inline]
 call_netdevice_notifiers net/core/dev.c:2294 [inline]
 register_netdevice+0x15c6/0x1a70 net/core/dev.c:11443
 register_netdev+0x40/0x60 net/core/dev.c:11521
 sit_init_net+0x228/0x5c0 net/ipv6/sit.c:1859
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0x110/0x330 net/core/net_namespace.c:446
 copy_net_ns+0x3e3/0x570 net/core/net_namespace.c:581
 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:130
 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:226
 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3171
 __do_sys_unshare kernel/fork.c:3242 [inline]
 __se_sys_unshare kernel/fork.c:3240 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3240
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 13215:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 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:2540 [inline]
 slab_free mm/slub.c:6670 [inline]
 kfree+0x1c0/0x660 mm/slub.c:6878
 snmp6_free_dev net/ipv6/addrconf_core.c:247 [inline]
 in6_dev_finish_destroy_rcu+0x3b/0xa0 net/ipv6/addrconf_core.c:256
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xc8e/0x1720 kernel/rcu/tree.c:2857
 handle_softirqs+0x22b/0x7c0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x60/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

The buggy address belongs to the object at ffff88805711c000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 3580 bytes inside of
 freed 4096-byte region [ffff88805711c000, ffff88805711d000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x57118
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888030ce9101
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813ffb0500 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff888030ce9101
head: 00fff00000000040 ffff88813ffb0500 0000000000000000 dead000000000001
head: 0000000000000000 0000000000040004 00000000f5000000 ffff888030ce9101
head: 00fff00000000003 ffffea00015c4601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5827, tgid 5827 (syz-executor), ts 89396198142, free_ts 27691354962
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
 prep_new_page mm/page_alloc.c:1865 [inline]
 get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xe53/0x1820 mm/slub.c:4656
 __slab_alloc+0x65/0x100 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0x5d4/0x820 mm/slub.c:5764
 kmemdup_noprof+0x2b/0x70 mm/util.c:138
 kmemdup_noprof include/linux/fortify-string.h:765 [inline]
 __addrconf_sysctl_register+0x9e/0x4c0 net/ipv6/addrconf.c:7305
 addrconf_sysctl_register+0x168/0x1c0 net/ipv6/addrconf.c:7371
 ipv6_add_dev+0xd26/0x13a0 net/ipv6/addrconf.c:460
 addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3650
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2280 [inline]
 call_netdevice_notifiers net/core/dev.c:2294 [inline]
 register_netdevice+0x15c6/0x1a70 net/core/dev.c:11443
 nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1061 [inline]
 nsim_create+0xb3f/0x1050 drivers/net/netdevsim/netdev.c:1143
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
 __free_pages mm/page_alloc.c:5329 [inline]
 free_contig_range+0x1bd/0x490 mm/page_alloc.c:7197
 destroy_args+0x69/0x660 mm/debug_vm_pgtable.c:983
 debug_vm_pgtable+0x38f/0x3a0 mm/debug_vm_pgtable.c:1372
 do_one_initcall+0x1f1/0x800 init/main.c:1378
 do_initcall_level+0x104/0x190 init/main.c:1440
 do_initcalls+0x59/0xa0 init/main.c:1456
 kernel_init_freeable+0x2a7/0x3d0 init/main.c:1688
 kernel_init+0x1d/0x1d0 init/main.c:1578
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Memory state around the buggy address:
 ffff88805711cc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805711cd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805711cd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff88805711ce00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805711ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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