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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 detach_if_pending+0x155/0x330 kernel/time/timer.c:841
Write of size 8 at addr ffff8881e15571c8 by task syz.4.92/681

CPU: 0 PID: 681 Comm: syz.4.92 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:
 __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]
 detach_if_pending+0x155/0x330 kernel/time/timer.c:841
 try_to_del_timer_sync kernel/time/timer.c:1267 [inline]
 del_timer_sync+0x136/0x1a0 kernel/time/timer.c:1410
 tun_flow_uninit+0x2f/0x2b0 drivers/net/tun.c:1452
 tun_free_netdev+0x7a/0x1b0 drivers/net/tun.c:2404
 netdev_run_todo+0xa45/0xc70 net/core/dev.c:9477
 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112
 tun_detach drivers/net/tun.c:766 [inline]
 tun_chr_close+0xc4/0x140 drivers/net/tun.c:3563
 __fput+0x2a3/0x730 fs/file_table.c:281
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x146/0x170 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x195/0x1b0 arch/x86/entry/common.c:163
 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
RIP: 0033:0x7f08f1b7c5ca
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 43 91 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 a3 91 02 00 8b 44 24
RSP: 002b:00007fff63beb900 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f08f1b7c5ca
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f08f1da6ba0 R08: 0000000000000138 R09: 0000001163bebc0f
R10: 00000000003ffca4 R11: 0000000000000293 R12: 000000000000769a
R13: 00007fff63beba10 R14: ffffffffffffffff R15: 00007fff63beba30

Allocated by task 683:
 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_symlinkat fs/namei.c:4317 [inline]
 __se_sys_symlinkat fs/namei.c:4314 [inline]
 __x64_sys_symlinkat+0x7b/0x90 fs/namei.c:4314
 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Freed by task 10:
 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 ffff8881e1557090
 which belongs to the cache shmem_inode_cache of size 760
The buggy address is located 312 bytes inside of
 760-byte region [ffff8881e1557090, ffff8881e1557388)
The buggy address belongs to the page:
page:ffffea0007855500 refcount:1 mapcount:0 mapping:ffff8881f5d02280 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5d02280
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_pages_ok+0x7e4/0x910 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4956 [inline]
 __free_pages+0x8c/0x110 mm/page_alloc.c:4962
 kfree+0x1ca/0x260 mm/slub.c:4068
 kvfree+0x4c/0x50 mm/util.c:625
 netdev_freemem+0x3f/0x60 net/core/dev.c:9583
 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1743
 device_release+0x70/0x1a0 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+0x1fe/0x2c0 lib/kobject.c:764
 put_device+0x1f/0x30 drivers/base/core.c:3010
 free_netdev+0x27e/0x320 net/core/dev.c:9746
 tun_set_iff+0x87c/0xe00 drivers/net/tun.c:2924
 __tun_chr_ioctl+0x771/0x18a0 drivers/net/tun.c:3187
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:3470
 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

Memory state around the buggy address:
 ffff8881e1557080: fc fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e1557100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881e1557180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8881e1557200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e1557280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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