syzbot

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BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:30 [inline]
BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]
BUG: KASAN: use-after-free in __linkwatch_run_queue+0x69b/0x7e0 net/core/link_watch.c:245
Read of size 1 at addr ffff888065844cc5 by task kworker/u8:6/25286

CPU: 0 UID: 0 PID: 25286 Comm: kworker/u8:6 Not tainted 6.15.0-rc4-syzkaller-00147-gebd297a2affa #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xb4/0x290 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 netdev_need_ops_lock include/net/netdev_lock.h:30 [inline]
 netdev_unlock_ops include/net/netdev_lock.h:47 [inline]
 __linkwatch_run_queue+0x69b/0x7e0 net/core/link_watch.c:245
 linkwatch_event+0x4c/0x60 net/core/link_watch.c:304
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4e/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888065844000 pfn:0x65844
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea000125f408 ffff8880b883f780 0000000000000000
raw: ffff888065844000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x446dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP), pid 27835, tgid 27828 (syz.8.5971), ts 1841001444980, free_ts 1842109960752
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1d8/0x230 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x21ce/0x22b0 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4970
 __alloc_pages_noprof+0xa/0x30 mm/page_alloc.c:5004
 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
 ___kmalloc_large_node+0x85/0x200 mm/slub.c:4285
 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:4313
 __do_kmalloc_node mm/slub.c:4329 [inline]
 __kvmalloc_node_noprof+0x74/0x5e0 mm/slub.c:5026
 alloc_netdev_mqs+0xa6/0x11e0 net/core/dev.c:11616
 tun_set_iff+0x532/0xef0 drivers/net/tun.c:2752
 __tun_chr_ioctl+0x788/0x1d90 drivers/net/tun.c:3048
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 27835 tgid 27828 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0xb0e/0xcd0 mm/page_alloc.c:2725
 __folio_put+0x21b/0x2c0 mm/swap.c:112
 folio_put include/linux/mm.h:1580 [inline]
 free_large_kmalloc+0x145/0x200 mm/slub.c:4781
 device_release+0x9c/0x1c0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22b/0x480 lib/kobject.c:737
 netdev_run_todo+0xd2e/0xea0 net/core/dev.c:11317
 tun_detach drivers/net/tun.c:639 [inline]
 tun_chr_close+0x13c/0x1c0 drivers/net/tun.c:3390
 __fput+0x44c/0xa70 fs/file_table.c:465
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x8d6/0x2550 kernel/exit.c:953
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x95/0x780 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x8b/0x120 kernel/entry/common.c:218
 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888065844b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888065844c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888065844c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff888065844d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888065844d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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