==================================================================
BUG: KASAN: slab-out-of-bounds in __hlist_del include/linux/list.h:791 [inline]
BUG: KASAN: slab-out-of-bounds in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: slab-out-of-bounds in expire_timers kernel/time/timer.c:1452 [inline]
BUG: KASAN: slab-out-of-bounds in __run_timers+0x7be/0xbe0 kernel/time/timer.c:1787
Write of size 8 at addr ffff8881db9f31c8 by task syz-executor.3/28695

CPU: 0 PID: 28695 Comm: syz-executor.3 Not tainted 5.4.265-syzkaller-00002-g50cb39f34248 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x241 lib/dump_stack.c:118
 print_address_description+0x8c/0x600 mm/kasan/report.c:384
 __kasan_report+0xf3/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 __hlist_del include/linux/list.h:791 [inline]
 detach_timer kernel/time/timer.c:824 [inline]
 expire_timers kernel/time/timer.c:1452 [inline]
 __run_timers+0x7be/0xbe0 kernel/time/timer.c:1787
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1800
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x195/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:538 [inline]
 smp_apic_timer_interrupt+0x11a/0x460 arch/x86/kernel/apic/apic.c:1149
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>

Allocated by task 28641:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 __kmalloc_track_caller+0x100/0x2b0 mm/slub.c:4449
 kmemdup+0x21/0x50 mm/util.c:127
 __addrconf_sysctl_register+0xad/0x3e0 net/ipv6/addrconf.c:6928
 addrconf_sysctl_register+0x128/0x180 net/ipv6/addrconf.c:6993
 ipv6_add_dev+0xb34/0x10a0 net/ipv6/addrconf.c:444
 addrconf_notify+0x59b/0xe50 net/ipv6/addrconf.c:3539
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406
 call_netdevice_notifiers_info net/core/dev.c:1670 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1682 [inline]
 call_netdevice_notifiers net/core/dev.c:1696 [inline]
 register_netdevice+0xeef/0x12a0 net/core/dev.c:9213
 register_netdev+0x37/0x50 net/core/dev.c:9311
 ip6gre_init_net+0x244/0x310 net/ipv6/ip6_gre.c:1611
 ops_init+0x1d4/0x4a0 net/core/net_namespace.c:138
 setup_net+0x214/0x990 net/core/net_namespace.c:345
 copy_net_ns+0x30f/0x510 net/core/net_namespace.c:486
 create_new_namespaces+0x47a/0x570 kernel/nsproxy.c:103
 copy_namespaces+0x169/0x1b0 kernel/nsproxy.c:161
 copy_process+0x12da/0x3230 kernel/fork.c:2055
 _do_fork+0x197/0x900 kernel/fork.c:2399
 __do_sys_clone kernel/fork.c:2557 [inline]
 __se_sys_clone kernel/fork.c:2538 [inline]
 __x64_sys_clone+0x26b/0x2c0 kernel/fork.c:2538
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Freed by task 179:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook mm/slub.c:1494 [inline]
 slab_free mm/slub.c:3080 [inline]
 kfree+0x123/0x370 mm/slub.c:4071
 __addrconf_sysctl_unregister net/ipv6/addrconf.c:6977 [inline]
 addrconf_sysctl_unregister net/ipv6/addrconf.c:7003 [inline]
 addrconf_ifdown+0x17b6/0x1a90 net/ipv6/addrconf.c:3910
 addrconf_notify+0x375/0xe50 net/ipv6/addrconf.c:3681
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406
 call_netdevice_notifiers_info net/core/dev.c:1670 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1682 [inline]
 call_netdevice_notifiers net/core/dev.c:1696 [inline]
 rollback_registered_many+0xce5/0x1330 net/core/dev.c:8623
 unregister_netdevice_many+0x46/0x250 net/core/dev.c:9778
 ip6gre_exit_batch_net+0x5b2/0x600 net/ipv6/ip6_gre.c:1633
 ops_exit_list net/core/net_namespace.c:184 [inline]
 cleanup_net+0x6e2/0xc90 net/core/net_namespace.c:609
 process_one_work+0x765/0xd20 kernel/workqueue.c:2290
 worker_thread+0xaef/0x1470 kernel/workqueue.c:2436
 kthread+0x2da/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354

The buggy address belongs to the object at ffff8881db9f2000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 456 bytes to the right of
 4096-byte region [ffff8881db9f2000, ffff8881db9f3000)
The buggy address belongs to the page:
page:ffffea00076e7c00 refcount:1 mapcount:0 mapping:ffff8881f5c0c280 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c0c280
raw: 0000000000000000 0000000000040004 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)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x18f/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4891
 alloc_slab_page+0x39/0x3c0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x440 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x2fe/0x490 mm/slub.c:2667
 __slab_alloc+0x62/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc_trace+0x12d/0x260 mm/slub.c:2854
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 kobject_uevent_env+0x26f/0x710 lib/kobject_uevent.c:524
 netdev_queue_add_kobject net/core/net-sysfs.c:1578 [inline]
 netdev_queue_update_kobjects+0x1a6/0x3a0 net/core/net-sysfs.c:1595
 register_queue_kobjects net/core/net-sysfs.c:1637 [inline]
 netdev_register_kobject+0x263/0x310 net/core/net-sysfs.c:1858
 register_netdevice+0xbc5/0x12a0 net/core/dev.c:9182
 register_netdev+0x37/0x50 net/core/dev.c:9311
 ip6gre_init_net+0x244/0x310 net/ipv6/ip6_gre.c:1611
 ops_init+0x1d4/0x4a0 net/core/net_namespace.c:138
 setup_net+0x214/0x990 net/core/net_namespace.c:345
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4953 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4959
 free_thread_stack kernel/fork.c:299 [inline]
 release_task_stack kernel/fork.c:439 [inline]
 put_task_stack+0x212/0x260 kernel/fork.c:450
 finish_task_switch+0x24a/0x590 kernel/sched/core.c:3479
 context_switch kernel/sched/core.c:3611 [inline]
 __schedule+0xb0d/0x1320 kernel/sched/core.c:4307
 preempt_schedule_irq+0xc7/0x140 kernel/sched/core.c:4558
 restore_regs_and_return_to_kernel+0x0/0x26

Memory state around the buggy address:
 ffff8881db9f3080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881db9f3100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881db9f3180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff8881db9f3200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881db9f3280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1ea7c1067 P4D 1ea7c1067 PUD 1eab1f067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 28695 Comm: syz-executor.3 Tainted: G    B             5.4.265-syzkaller-00002-g50cb39f34248 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6e09d18 EFLAGS: 00010202
RAX: ffffffff8154e38a RBX: 0000000000000101 RCX: ffff8881e471ee40
RDX: 0000000000000101 RSI: 0000000000000000 RDI: ffff8881db9f31c0
RBP: ffff8881f6e09ec8 R08: ffffffff8154dfce R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 0000000100006d68
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881db9f31c0
FS:  00007f69064ff6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001f2fcd000 CR4: 00000000003406b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 call_timer_fn+0x36/0x390 kernel/time/timer.c:1418
 expire_timers kernel/time/timer.c:1463 [inline]
 __run_timers+0x879/0xbe0 kernel/time/timer.c:1787
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1800
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x195/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:538 [inline]
 smp_apic_timer_interrupt+0x11a/0x460 arch/x86/kernel/apic/apic.c:1149
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
Modules linked in:
CR2: 0000000000000000
---[ end trace b5a875b7ef07e314 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6e09d18 EFLAGS: 00010202
RAX: ffffffff8154e38a RBX: 0000000000000101 RCX: ffff8881e471ee40
RDX: 0000000000000101 RSI: 0000000000000000 RDI: ffff8881db9f31c0
RBP: ffff8881f6e09ec8 R08: ffffffff8154dfce R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 0000000100006d68
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881db9f31c0
FS:  00007f69064ff6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001f2fcd000 CR4: 00000000003406b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600