==================================================================
BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline]
BUG: KASAN: use-after-free in enqueue_timer+0xb7/0x300 kernel/time/timer.c:541
Write of size 8 at addr ffff8881e6c031c8 by task ksoftirqd/0/10

CPU: 0 PID: 10 Comm: ksoftirqd/0 Not tainted 5.4.290-syzkaller-00017-g6b07fcd94a6a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 __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_add_head include/linux/list.h:814 [inline]
 enqueue_timer+0xb7/0x300 kernel/time/timer.c:541
 __internal_add_timer kernel/time/timer.c:554 [inline]
 internal_add_timer+0x240/0x430 kernel/time/timer.c:604
 __mod_timer+0x6f1/0x13e0 kernel/time/timer.c:1065
 call_timer_fn+0x36/0x390 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1493 [inline]
 __run_timers+0x879/0xbe0 kernel/time/timer.c:1817
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292
 run_ksoftirqd+0x1f/0x30 kernel/softirq.c:603
 smpboot_thread_fn+0x545/0x930 kernel/smpboot.c:165
 kthread+0x2da/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354

Allocated by task 125:
 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
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xb4/0x4d0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1080 [inline]
 nlmsg_new include/net/netlink.h:888 [inline]
 inet6_ifa_notify net/ipv6/addrconf.c:5459 [inline]
 __ipv6_ifa_notify+0x2e1/0x1290 net/ipv6/addrconf.c:6068
 ipv6_ifa_notify net/ipv6/addrconf.c:6121 [inline]
 addrconf_dad_completed+0x181/0xdb0 net/ipv6/addrconf.c:4234
 addrconf_dad_work+0xe4d/0x16f0 net/ipv6/addrconf.c:4038
 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

Freed by task 125:
 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
 skb_release_all net/core/skbuff.c:675 [inline]
 __kfree_skb net/core/skbuff.c:689 [inline]
 consume_skb+0xa5/0x2a0 net/core/skbuff.c:849
 netlink_broadcast_filtered+0x115f/0x1280 net/netlink/af_netlink.c:1516
 netlink_broadcast net/netlink/af_netlink.c:1538 [inline]
 nlmsg_multicast include/net/netlink.h:968 [inline]
 nlmsg_notify+0xf7/0x1b0 net/netlink/af_netlink.c:2510
 inet6_ifa_notify net/ipv6/addrconf.c:5470 [inline]
 __ipv6_ifa_notify+0x32a/0x1290 net/ipv6/addrconf.c:6068
 ipv6_ifa_notify net/ipv6/addrconf.c:6121 [inline]
 addrconf_dad_completed+0x181/0xdb0 net/ipv6/addrconf.c:4234
 addrconf_dad_work+0xe4d/0x16f0 net/ipv6/addrconf.c:4038
 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 ffff8881e6c03000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 456 bytes inside of
 512-byte region [ffff8881e6c03000, ffff8881e6c03200)
The buggy address belongs to the page:
page:ffffea00079b0000 refcount:1 mapcount:0 mapping:ffff8881f5c02500 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c02500
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__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:4893
 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]
 __kmalloc_track_caller+0x16d/0x2b0 mm/slub.c:4449
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xb4/0x4d0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1080 [inline]
 nlmsg_new include/net/netlink.h:888 [inline]
 inet6_ifa_notify net/ipv6/addrconf.c:5459 [inline]
 __ipv6_ifa_notify+0x2e1/0x1290 net/ipv6/addrconf.c:6068
 ipv6_ifa_notify net/ipv6/addrconf.c:6121 [inline]
 addrconf_dad_completed+0x181/0xdb0 net/ipv6/addrconf.c:4234
 addrconf_dad_work+0xe4d/0x16f0 net/ipv6/addrconf.c:4038
 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
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:4955 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4961
 device_release+0x6b/0x190 drivers/base/core.c:1776
 kobject_cleanup lib/kobject.c:716 [inline]
 kobject_release lib/kobject.c:747 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e6/0x2f0 lib/kobject.c:764
 tun_set_iff+0x870/0xdc0 drivers/net/tun.c:2924
 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3187
 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881e6c03080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e6c03100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881e6c03180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8881e6c03200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881e6c03280: 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 1d484d067 P4D 1d484d067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 586 Comm: syz.0.59 Tainted: G    B             5.4.290-syzkaller-00017-g6b07fcd94a6a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6e09d18 EFLAGS: 00010206
RAX: ffffffff8154e8ca RBX: 0000000000000100 RCX: ffff8881e6da6e40
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8881e6c031c0
RBP: ffff8881f6e09ec8 R08: ffffffff8154e50e R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffff9758
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e6c031c0
FS:  00007f5518f3a6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001d18e0000 CR4: 00000000003406b0
DR0: 00000000000003ff DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 call_timer_fn+0x36/0x390 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1493 [inline]
 __run_timers+0x879/0xbe0 kernel/time/timer.c:1817
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1830
 __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:539 [inline]
 smp_apic_timer_interrupt+0x11a/0x490 arch/x86/kernel/apic/apic.c:1161
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_cmp4+0x1b/0x70 kernel/kcov.c:249
Code: 0a 18 4c 89 44 0a 20 49 ff c1 4c 89 09 c3 90 4c 8b 04 24 65 48 8b 05 44 41 9e 7e 65 8b 0d 49 41 9e 7e f7 c1 00 01 1f 00 74 01 <c3> 8b 88 00 0a 00 00 83 f9 03 75 f4 48 8b 88 08 0a 00 00 44 8b 90
RSP: 0018:ffff8881e560f520 EFLAGS: 00000297 ORIG_RAX: ffffffffffffff13
RAX: ffff8881e6da6e40 RBX: 0000000000000004 RCX: 0000000000000002
RDX: ffffc90000940000 RSI: 0000000000000010 RDI: 0000000000000004
RBP: 0000000000000010 R08: ffffffff8153c592 R09: ffff8881e560f5d0
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff1103cac1ecd
R13: 0000000000000003 R14: dffffc0000000000 R15: 1ffff1103cac1ece
 stack_trace_consume_entry+0x162/0x240 kernel/stacktrace.c:94
 arch_stack_walk+0x105/0x140 arch/x86/kernel/stacktrace.c:27
 stack_trace_save+0x118/0x1c0 kernel/stacktrace.c:123
 save_stack+0x95/0x880 mm/page_owner.c:122
 __reset_page_owner+0x1f/0x100 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 free_pcp_prepare mm/page_alloc.c:1233 [inline]
 free_unref_page_prepare+0x297/0x380 mm/page_alloc.c:3085
 free_unref_page mm/page_alloc.c:3134 [inline]
 free_the_page mm/page_alloc.c:4953 [inline]
 __free_pages mm/page_alloc.c:4961 [inline]
 free_pages+0x114/0x1b0 mm/page_alloc.c:4969
 tlb_batch_list_free mm/mmu_gather.c:61 [inline]
 tlb_finish_mmu+0x249/0x320 mm/mmu_gather.c:280
 exit_mmap+0x2dc/0x520 mm/mmap.c:3193
 __mmput+0x8e/0x2c0 kernel/fork.c:1101
 copy_process+0x1f42/0x3230 kernel/fork.c:2298
 _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
RIP: 0033:0x7f551a8d0169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5518f39fe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f551aae8fa0 RCX: 00007f551a8d0169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000024001000
RBP: 00007f551a9512a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f551aae8fa0 R15: 00007ffe8cb891e8
Modules linked in:
CR2: 0000000000000000
---[ end trace 13164f4532523935 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6e09d18 EFLAGS: 00010206
RAX: ffffffff8154e8ca RBX: 0000000000000100 RCX: ffff8881e6da6e40
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8881e6c031c0
RBP: ffff8881f6e09ec8 R08: ffffffff8154e50e R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffff9758
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e6c031c0
FS:  00007f5518f3a6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001d18e0000 CR4: 00000000003406b0
DR0: 00000000000003ff DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
----------------
Code disassembly (best guess):
   0:	0a 18                	or     (%rax),%bl
   2:	4c 89 44 0a 20       	mov    %r8,0x20(%rdx,%rcx,1)
   7:	49 ff c1             	inc    %r9
   a:	4c 89 09             	mov    %r9,(%rcx)
   d:	c3                   	ret
   e:	90                   	nop
   f:	4c 8b 04 24          	mov    (%rsp),%r8
  13:	65 48 8b 05 44 41 9e 	mov    %gs:0x7e9e4144(%rip),%rax        # 0x7e9e415f
  1a:	7e
  1b:	65 8b 0d 49 41 9e 7e 	mov    %gs:0x7e9e4149(%rip),%ecx        # 0x7e9e416b
  22:	f7 c1 00 01 1f 00    	test   $0x1f0100,%ecx
  28:	74 01                	je     0x2b
* 2a:	c3                   	ret <-- trapping instruction
  2b:	8b 88 00 0a 00 00    	mov    0xa00(%rax),%ecx
  31:	83 f9 03             	cmp    $0x3,%ecx
  34:	75 f4                	jne    0x2a
  36:	48 8b 88 08 0a 00 00 	mov    0xa08(%rax),%rcx
  3d:	44                   	rex.R
  3e:	8b                   	.byte 0x8b
  3f:	90                   	nop