==================================================================
BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:791 [inline]
BUG: KASAN: use-after-free in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: use-after-free in expire_timers kernel/time/timer.c:1482 [inline]
BUG: KASAN: use-after-free in __run_timers+0x759/0xb60 kernel/time/timer.c:1817
Write of size 8 at addr ffff8881e60ef1c8 by task syz.3.102/735

CPU: 1 PID: 735 Comm: syz.3.102 Not tainted 5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <IRQ>
 __dump_stack+0x1e/0x20 lib/dump_stack.c:77
 dump_stack+0x15b/0x1b8 lib/dump_stack.c:118
 print_address_description+0x8d/0x4c0 mm/kasan/report.c:384
 __kasan_report+0xef/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:137
 __hlist_del include/linux/list.h:791 [inline]
 detach_timer kernel/time/timer.c:824 [inline]
 expire_timers kernel/time/timer.c:1482 [inline]
 __run_timers+0x759/0xb60 kernel/time/timer.c:1817
 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x236/0x660 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x197/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:539 [inline]
 smp_apic_timer_interrupt+0x11d/0x490 arch/x86/kernel/apic/apic.c:1161
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0010:check_kcov_mode kernel/kcov.c:164 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x50 kernel/kcov.c:187
Code: 90 90 00 55 48 89 e5 48 8b 45 08 65 48 8b 0d 90 0e a3 7e 65 8b 15 95 0e a3 7e f7 c2 00 01 1f 00 74 02 5d c3 8b 91 00 0a 00 00 <83> fa 02 75 f3 48 8b 91 08 0a 00 00 48 8b 32 48 8d 7e 01 8b 89 04
RSP: 0018:ffff8881e1ee7590 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff83b4a7dd RBX: ffff8881d6c20720 RCX: ffff8881ec9e6e40
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8881e1ee7590 R08: dffffc0000000000 R09: ffffed103b02200a
R10: ffffed103b02200a R11: 1ffff1103b022009 R12: ffff8881e1ee7600
R13: 0000000000000000 R14: 0000000000000053 R15: ffff8881d6c20000
 __fib6_clean_all net/ipv6/ip6_fib.c:2152 [inline]
 fib6_clean_all+0x10d/0x230 net/ipv6/ip6_fib.c:2165
 rt6_sync_up+0x11d/0x150 net/ipv6/route.c:4670
 addrconf_notify+0xa5c/0xeb0 net/ipv6/addrconf.c:3669
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0xa0/0x120 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]
 __dev_notify_flags+0x1e2/0x3d0 net/core/dev.c:-1
 dev_change_flags+0xe8/0x1a0 net/core/dev.c:8034
 dev_ifsioc+0x110/0xa40 net/core/dev_ioctl.c:226
 dev_ioctl+0x550/0xb80 net/core/dev_ioctl.c:483
 sock_do_ioctl+0x235/0x330 net/socket.c:1081
 sock_ioctl+0x505/0x710 net/socket.c:1198
 do_vfs_ioctl+0x753/0x13f0 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+0xe1/0x120 fs/ioctl.c:747
 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f132f13f969
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:00007f132d7a8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f132f366fa0 RCX: 00007f132f13f969
RDX: 0000200000000900 RSI: 0000000000008914 RDI: 0000000000000007
RBP: 00007f132f1c1ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f132f366fa0 R15: 00007ffe22547e68

Allocated by task 337:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x162/0x200 mm/kasan/common.c:529
 kasan_slab_alloc+0x12/0x20 mm/kasan/common.c:537
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0xe2/0x270 mm/slub.c:2842
 shmem_alloc_inode+0x1a/0x30 mm/shmem.c:3719
 alloc_inode fs/inode.c:231 [inline]
 new_inode_pseudo+0x62/0x210 fs/inode.c:966
 new_inode+0x28/0x1e0 fs/inode.c:995
 shmem_get_inode+0x107/0x630 mm/shmem.c:2252
 shmem_symlink+0x9e/0x4d0 mm/shmem.c:3068
 vfs_symlink+0x337/0x4c0 fs/namei.c:4276
 do_symlinkat+0x103/0x3b0 fs/namei.c:4303
 __do_sys_symlink fs/namei.c:4322 [inline]
 __se_sys_symlink fs/namei.c:4320 [inline]
 __x64_sys_symlink+0x60/0x70 fs/namei.c:4320
 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Freed by task 17:
 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+0x1c3/0x280 mm/kasan/common.c:487
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:496
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook+0xb7/0x180 mm/slub.c:1494
 slab_free mm/slub.c:3080 [inline]
 kmem_cache_free+0x10c/0x2c0 mm/slub.c:3096
 shmem_free_in_core_inode+0x90/0xb0 mm/shmem.c:3729
 i_callback+0x4c/0x70 fs/inode.c:220
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch+0x446/0x980 kernel/rcu/tree.c:2167
 rcu_core+0x4bd/0xbd0 kernel/rcu/tree.c:2387
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2396
 __do_softirq+0x236/0x660 kernel/softirq.c:292

The buggy address belongs to the object at ffff8881e60ef090
 which belongs to the cache shmem_inode_cache of size 760
The buggy address is located 312 bytes inside of
 760-byte region [ffff8881e60ef090, ffff8881e60ef388)
The buggy address belongs to the page:
page:ffffea0007983b00 refcount:1 mapcount:0 mapping:ffff8881f5d03680 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5d03680
raw: 0000000000000000 0000000000120012 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 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+0x35e/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x1296/0x1310 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x202/0x4b0 mm/page_alloc.c:4894
 alloc_slab_page+0x3c/0x3b0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x93/0x420 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x29e/0x420 mm/slub.c:2667
 __slab_alloc+0x63/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0x12c/0x270 mm/slub.c:2842
 shmem_alloc_inode+0x1a/0x30 mm/shmem.c:3719
 alloc_inode fs/inode.c:231 [inline]
 new_inode_pseudo+0x62/0x210 fs/inode.c:966
 new_inode+0x28/0x1e0 fs/inode.c:995
 shmem_get_inode+0x107/0x630 mm/shmem.c:2252
 shmem_symlink+0x9e/0x4d0 mm/shmem.c:3068
 vfs_symlink+0x337/0x4c0 fs/namei.c:4276
 do_symlinkat+0x103/0x3b0 fs/namei.c:4303
 __do_sys_symlinkat fs/namei.c:4317 [inline]
 __se_sys_symlinkat fs/namei.c:4314 [inline]
 __x64_sys_symlinkat+0x7b/0x90 fs/namei.c:4314
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_pcp_prepare mm/page_alloc.c:1233 [inline]
 free_unref_page_prepare+0x2a9/0x3a0 mm/page_alloc.c:3085
 free_unref_page_list+0x110/0x4c0 mm/page_alloc.c:3154
 release_pages+0xa62/0xaa0 mm/swap.c:842
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:297
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:189 [inline]
 tlb_flush_mmu mm/mmu_gather.c:196 [inline]
 tlb_finish_mmu+0x175/0x300 mm/mmu_gather.c:277
 exit_mmap+0x2db/0x520 mm/mmap.c:3193
 __mmput+0x92/0x2e0 kernel/fork.c:1101
 mmput+0x47/0x60 kernel/fork.c:1122
 exit_mm kernel/exit.c:538 [inline]
 do_exit+0x99f/0x2660 kernel/exit.c:848
 do_group_exit+0x13e/0x300 kernel/exit.c:984
 get_signal+0xdee/0x13d0 kernel/signal.c:2738
 do_signal+0xad/0xda0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0xc4/0x1b0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode+0x18e/0x1f0 arch/x86/entry/common.c:194
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x13e/0x170 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881e60ef080: fc fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e60ef100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881e60ef180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8881e60ef200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e60ef280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1e2485067 P4D 1e2485067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 735 Comm: syz.3.102 Tainted: G    B             5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09cf0 EFLAGS: 00010206
RAX: ffffffff8150a590 RBX: 0000000000000100 RCX: ffff8881ec9e6e40
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8881e60ef1c0
RBP: ffff8881f6f09d30 R08: dffffc0000000000 R09: ffffed103ede92a1
R10: ffffed103ede92a1 R11: 1ffff1103ede92a0 R12: 00000000ffff9948
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e60ef1c0
FS:  00007f132d7a86c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001e23f9000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 call_timer_fn+0x3c/0x380 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1493 [inline]
 __run_timers+0x81d/0xb60 kernel/time/timer.c:1817
 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x236/0x660 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x197/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:539 [inline]
 smp_apic_timer_interrupt+0x11d/0x490 arch/x86/kernel/apic/apic.c:1161
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0010:check_kcov_mode kernel/kcov.c:164 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x50 kernel/kcov.c:187
Code: 90 90 00 55 48 89 e5 48 8b 45 08 65 48 8b 0d 90 0e a3 7e 65 8b 15 95 0e a3 7e f7 c2 00 01 1f 00 74 02 5d c3 8b 91 00 0a 00 00 <83> fa 02 75 f3 48 8b 91 08 0a 00 00 48 8b 32 48 8d 7e 01 8b 89 04
RSP: 0018:ffff8881e1ee7590 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff83b4a7dd RBX: ffff8881d6c20720 RCX: ffff8881ec9e6e40
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8881e1ee7590 R08: dffffc0000000000 R09: ffffed103b02200a
R10: ffffed103b02200a R11: 1ffff1103b022009 R12: ffff8881e1ee7600
R13: 0000000000000000 R14: 0000000000000053 R15: ffff8881d6c20000
 __fib6_clean_all net/ipv6/ip6_fib.c:2152 [inline]
 fib6_clean_all+0x10d/0x230 net/ipv6/ip6_fib.c:2165
 rt6_sync_up+0x11d/0x150 net/ipv6/route.c:4670
 addrconf_notify+0xa5c/0xeb0 net/ipv6/addrconf.c:3669
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0xa0/0x120 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]
 __dev_notify_flags+0x1e2/0x3d0 net/core/dev.c:-1
 dev_change_flags+0xe8/0x1a0 net/core/dev.c:8034
 dev_ifsioc+0x110/0xa40 net/core/dev_ioctl.c:226
 dev_ioctl+0x550/0xb80 net/core/dev_ioctl.c:483
 sock_do_ioctl+0x235/0x330 net/socket.c:1081
 sock_ioctl+0x505/0x710 net/socket.c:1198
 do_vfs_ioctl+0x753/0x13f0 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+0xe1/0x120 fs/ioctl.c:747
 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f132f13f969
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:00007f132d7a8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f132f366fa0 RCX: 00007f132f13f969
RDX: 0000200000000900 RSI: 0000000000008914 RDI: 0000000000000007
RBP: 00007f132f1c1ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f132f366fa0 R15: 00007ffe22547e68
Modules linked in:
CR2: 0000000000000000
---[ end trace 944bb4ea5b0a5a3e ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09cf0 EFLAGS: 00010206
RAX: ffffffff8150a590 RBX: 0000000000000100 RCX: ffff8881ec9e6e40
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8881e60ef1c0
RBP: ffff8881f6f09d30 R08: dffffc0000000000 R09: ffffed103ede92a1
R10: ffffed103ede92a1 R11: 1ffff1103ede92a0 R12: 00000000ffff9948
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e60ef1c0
FS:  00007f132d7a86c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001e23f9000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	90                   	nop
   2:	00 55 48             	add    %dl,0x48(%rbp)
   5:	89 e5                	mov    %esp,%ebp
   7:	48 8b 45 08          	mov    0x8(%rbp),%rax
   b:	65 48 8b 0d 90 0e a3 	mov    %gs:0x7ea30e90(%rip),%rcx        # 0x7ea30ea3
  12:	7e
  13:	65 8b 15 95 0e a3 7e 	mov    %gs:0x7ea30e95(%rip),%edx        # 0x7ea30eaf
  1a:	f7 c2 00 01 1f 00    	test   $0x1f0100,%edx
  20:	74 02                	je     0x24
  22:	5d                   	pop    %rbp
  23:	c3                   	ret
  24:	8b 91 00 0a 00 00    	mov    0xa00(%rcx),%edx
* 2a:	83 fa 02             	cmp    $0x2,%edx <-- trapping instruction
  2d:	75 f3                	jne    0x22
  2f:	48 8b 91 08 0a 00 00 	mov    0xa08(%rcx),%rdx
  36:	48 8b 32             	mov    (%rdx),%rsi
  39:	48 8d 7e 01          	lea    0x1(%rsi),%rdi
  3d:	8b                   	.byte 0x8b
  3e:	89                   	.byte 0x89
  3f:	04                   	.byte 0x4