[PATCH] macintosh/mac_hid: fix race condition in mac_hid_toggle_emumouse

[Madhavan Srinivasan]

On Tue, 19 Aug 2025 17:10:35 +0800, leo.lilong at huaweicloud.com wrote:
> The following warning appears when running syzkaller, and this issue also
> exists in the mainline code.
> 
>  ------------[ cut here ]------------
>  list_add double add: new=ffffffffa57eee28, prev=ffffffffa57eee28, next=ffffffffa5e63100.
>  WARNING: CPU: 0 PID: 1491 at lib/list_debug.c:35 __list_add_valid_or_report+0xf7/0x130
>  Modules linked in:
>  CPU: 0 PID: 1491 Comm: syz.1.28 Not tainted 6.6.0+ #3
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
>  RIP: 0010:__list_add_valid_or_report+0xf7/0x130
>  RSP: 0018:ff1100010dfb7b78 EFLAGS: 00010282
>  RAX: 0000000000000000 RBX: ffffffffa57eee18 RCX: ffffffff97fc9817
>  RDX: 0000000000040000 RSI: ffa0000002383000 RDI: 0000000000000001
>  RBP: ffffffffa57eee28 R08: 0000000000000001 R09: ffe21c0021bf6f2c
>  R10: 0000000000000001 R11: 6464615f7473696c R12: ffffffffa5e63100
>  R13: ffffffffa57eee28 R14: ffffffffa57eee28 R15: ff1100010dfb7d48
>  FS:  00007fb14398b640(0000) GS:ff11000119600000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 0000000000000000 CR3: 000000010d096005 CR4: 0000000000773ef0
>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  PKRU: 80000000
>  Call Trace:
>   <TASK>
>   input_register_handler+0xb3/0x210
>   mac_hid_start_emulation+0x1c5/0x290
>   mac_hid_toggle_emumouse+0x20a/0x240
>   proc_sys_call_handler+0x4c2/0x6e0
>   new_sync_write+0x1b1/0x2d0
>   vfs_write+0x709/0x950
>   ksys_write+0x12a/0x250
>   do_syscall_64+0x5a/0x110
>   entry_SYSCALL_64_after_hwframe+0x78/0xe2
> 
> [...]

Applied to powerpc/next.

[1/1] macintosh/mac_hid: fix race condition in mac_hid_toggle_emumouse
      https://git.kernel.org/powerpc/c/1e4b207ffe54cf33a4b7a2912c4110f89c73bf3f

Thanks