list_add double add: new=ffff0000c8eee218, prev=ffff0000c8eee218, next=ffff0000da3be078.
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:37!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 0 UID: 0 PID: 6712 Comm: syz.4.1598 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 634000c5 (nZCv daIF +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __list_add_valid_or_report+0xbc/0x148 lib/list_debug.c:35
lr : __list_add_valid_or_report+0xbc/0x148 lib/list_debug.c:35
sp : ffff8000929a7700
x29: ffff8000929a7700 x28: 1fffe0001940c842 x27: 1fffe0001940c880
x26: 1fffe0001b477c10 x25: ffff0000c8eee218 x24: ffff0000da3be080
x23: 1fffe000191ddc43 x22: dfff800000000000 x21: ffff0000c8eee218
x20: ffff0000c8eee218 x19: ffff0000da3be078 x18: 1fffe00034bb7428
x17: 3831326565653863 x16: 3030303066666666 x15: 3d76657270202c38
x14: 3132656565386330 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000003 x9 : 5ffe9f7061c30e00
x8 : 5ffe9f7061c30e00 x7 : ffff80008048e8f8 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000000 x3 : ffff800080499634
x2 : 0000000100000002 x1 : ffff0000cc928000 x0 : 0000000000000058
Call trace:
 __list_add_valid_or_report+0xbc/0x148 lib/list_debug.c:35 (P)
 __list_add_valid include/linux/list.h:96 [inline]
 __list_add include/linux/list.h:158 [inline]
 list_add_tail include/linux/list.h:191 [inline]
 usb_hcd_link_urb_to_ep+0x17c/0x2d0 drivers/usb/core/hcd.c:1154
 dummy_urb_enqueue+0x250/0x690 drivers/usb/gadget/udc/dummy_hcd.c:1310
 usb_hcd_submit_urb+0x2dc/0x169c drivers/usb/core/hcd.c:1542
 usb_submit_urb+0xd44/0x1458 drivers/usb/core/urb.c:586
 keyspan_usa49_send_setup+0x780/0xce0 drivers/usb/serial/keyspan.c:2466
 keyspan_send_setup+0x11c/0x178 drivers/usb/serial/keyspan.c:2763
 keyspan_dtr_rts+0x8c/0xdc drivers/usb/serial/keyspan.c:1577
 serial_port_dtr_rts+0x90/0xac drivers/usb/serial/usb-serial.c:768
 tty_port_lower_dtr_rts drivers/tty/tty_port.c:471 [inline]
 tty_port_shutdown+0x130/0x204 drivers/tty/tty_port.c:369
 tty_port_close+0x54/0x110 drivers/tty/tty_port.c:705
 serial_close+0x5c/0xc8 drivers/usb/serial/usb-serial.c:326
 tty_release+0x2c4/0xffc drivers/tty/tty_io.c:1745
 __fput+0x338/0x74c fs/file_table.c:512
 ____fput+0x20/0x30 fs/file_table.c:540
 task_work_run+0x1cc/0x25c kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline]
 el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:739
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:757
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Code: aa1503e1 aa1403e2 aa1303e3 979c1e5a (d4210000) 
---[ end trace 0000000000000000 ]---