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BUG: KASAN: use-after-free in __write_once_size include/linux/compiler.h:295 [inline]
BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:789 [inline]
BUG: KASAN: use-after-free in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: use-after-free in detach_if_pending+0x160/0x360 kernel/time/timer.c:841
Write of size 8 at addr ffff8881e49871c0 by task syz-executor.2/3419

CPU: 1 PID: 3419 Comm: syz-executor.2 Not tainted 5.4.268-syzkaller-00012-gd0d34dcb02cc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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
 __write_once_size include/linux/compiler.h:295 [inline]
 __hlist_del include/linux/list.h:789 [inline]
 detach_timer kernel/time/timer.c:824 [inline]
 detach_if_pending+0x160/0x360 kernel/time/timer.c:841
 try_to_del_timer_sync kernel/time/timer.c:1238 [inline]
 del_timer_sync+0x13c/0x230 kernel/time/timer.c:1379
 tun_flow_uninit+0x2c/0x280 drivers/net/tun.c:1451
 tun_free_netdev+0x77/0x190 drivers/net/tun.c:2401
 netdev_run_todo+0xb7f/0xdf0 net/core/dev.c:9458
 tun_detach drivers/net/tun.c:765 [inline]
 tun_chr_close+0xc1/0x130 drivers/net/tun.c:3557
 __fput+0x262/0x680 fs/file_table.c:281
 task_work_run+0x140/0x170 kernel/task_work.c:113
 get_signal+0x13c6/0x1440 kernel/signal.c:2529
 do_signal+0xb0/0x11f0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0xc0/0x1a0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode+0x199/0x200 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Allocated by task 365:
 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]
 kmem_cache_alloc+0xd9/0x250 mm/slub.c:2842
 __sigqueue_alloc+0x19b/0x2e0 kernel/signal.c:435
 __send_signal+0x1ee/0xbe0 kernel/signal.c:1116
 do_send_sig_info+0xe0/0x130 kernel/signal.c:1291
 irq_work_run_list+0x1b0/0x240 kernel/irq_work.c:165
 irq_work_run+0x63/0xe0 kernel/irq_work.c:180
 smp_irq_work_interrupt+0x7f/0x250 arch/x86/kernel/irq_work.c:21

Freed by task 365:
 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]
 kmem_cache_free+0x10b/0x2c0 mm/slub.c:3096
 __sigqueue_free kernel/signal.c:458 [inline]
 collect_signal kernel/signal.c:597 [inline]
 __dequeue_signal+0x54f/0x630 kernel/signal.c:619
 dequeue_signal+0x10c/0x520 kernel/signal.c:639
 signalfd_dequeue fs/signalfd.c:163 [inline]
 signalfd_read+0x3a9/0x1330 fs/signalfd.c:217
 __vfs_read+0x103/0x730 fs/read_write.c:425
 vfs_read+0x148/0x360 fs/read_write.c:461
 ksys_read+0x199/0x2c0 fs/read_write.c:587
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

The buggy address belongs to the object at ffff8881e49871c0
 which belongs to the cache sigqueue of size 80
The buggy address is located 0 bytes inside of
 80-byte region [ffff8881e49871c0, ffff8881e4987210)
The buggy address belongs to the page:
page:ffffea00079261c0 refcount:1 mapcount:0 mapping:ffff8881f5d06000 index:0x0
flags: 0x8000000000000200(slab)
raw: 8000000000000200 dead000000000100 dead000000000122 ffff8881f5d06000
raw: 0000000000000000 0000000000240024 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__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+0x109/0x250 mm/slub.c:2842
 __sigqueue_alloc+0x19b/0x2e0 kernel/signal.c:435
 __send_signal+0x1ee/0xbe0 kernel/signal.c:1116
 do_send_sig_info+0xe0/0x130 kernel/signal.c:1291
 irq_work_run_list+0x1b0/0x240 kernel/irq_work.c:165
 irq_work_run+0x63/0xe0 kernel/irq_work.c:180
 smp_irq_work_interrupt+0x7f/0x250 arch/x86/kernel/irq_work.c:21
 irq_work_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:865
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
 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:2918
 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3181
 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:
 ffff8881e4987080: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
 ffff8881e4987100: fb fb fb fb fb fb fc fc fc fc fb fb fb fb fb fb
>ffff8881e4987180: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff8881e4987200: fb fb fc fc fc fc fb fb fb fb fb fb fb fb fb fb
 ffff8881e4987280: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fc fc
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