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BUG: KASAN: slab-out-of-bounds in __write_once_size include/linux/compiler.h:295 [inline]
BUG: KASAN: slab-out-of-bounds in __hlist_del include/linux/list.h:789 [inline]
BUG: KASAN: slab-out-of-bounds in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: slab-out-of-bounds in detach_if_pending+0x160/0x360 kernel/time/timer.c:841
Write of size 8 at addr ffff8881f29f71c0 by task syz-executor.1/1115

CPU: 1 PID: 1115 Comm: syz-executor.1 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
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xcaf/0x2bc0 kernel/exit.c:859
 do_group_exit+0x138/0x300 kernel/exit.c:982
 get_signal+0xdb1/0x1440 kernel/signal.c:2735
 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 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8881f29f7090
 which belongs to the cache shmem_inode_cache of size 760
The buggy address is located 304 bytes inside of
 760-byte region [ffff8881f29f7090, ffff8881f29f7388)
The buggy address belongs to the page:
page:ffffea0007ca7d00 refcount:1 mapcount:0 mapping:ffff8881f5d06780 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5d06780
raw: 0000000000000000 0000000080120012 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+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
 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3719
 alloc_inode fs/inode.c:231 [inline]
 new_inode_pseudo+0x60/0x210 fs/inode.c:927
 new_inode+0x25/0x1d0 fs/inode.c:956
 shmem_get_inode+0x10b/0x620 mm/shmem.c:2252
 shmem_mknod+0x54/0x1a0 mm/shmem.c:2844
 lookup_open fs/namei.c:3329 [inline]
 do_last fs/namei.c:3421 [inline]
 path_openat+0x181b/0x3480 fs/namei.c:3634
 do_filp_open+0x20b/0x450 fs/namei.c:3664
 do_sys_open+0x39c/0x810 fs/open.c:1113
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
 bpf_check+0x8aaa/0xb340 kernel/bpf/verifier.c:9731
 bpf_prog_load kernel/bpf/syscall.c:1724 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2891 [inline]
 __se_sys_bpf+0x8139/0xbcb0 kernel/bpf/syscall.c:2849
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881f29f7080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881f29f7100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881f29f7180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff8881f29f7200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881f29f7280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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