Re: [PATCH v2] HID: fix HID device resource race between HID core and debugging support

[Rahul Rameshbabu]

On Tue, 07 Nov, 2023 16:16:30 +0800 "Charles Yi" <be286@xxxxxxx> wrote:
> hid_debug_events_release releases resources bound to the HID device
> instance. hid_device_release releases the underlying HID device
> instance potentially before hid_debug_events_release has completed
> releasing debug resources bound to the same HID device instance.
>
> Reference count to prevent the HID device instance from being torn
> down preemptively when HID debugging support is used. When count
> reaches zero, release core resources of HID device instance using
> hid_hiddev_free.
>
> The crash:
> [  120.728477][ T4396] kernel BUG at lib/list_debug.c:53!
> [  120.728505][ T4396] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
> [  120.739806][ T4396] Modules linked in: bcmdhd dhd_static_buf 8822cu pcie_mhi r8168
> [  120.747386][ T4396] CPU: 1 PID: 4396 Comm: hidt_bridge Not tainted 5.10.110 #257
> [  120.754771][ T4396] Hardware name: Rockchip RK3588 EVB4 LP4 V10 Board (DT)
> [  120.761643][ T4396] pstate: 60400089 (nZCv daIf +PAN -UAO -TCO BTYPE=--)
> [  120.768338][ T4396] pc : __list_del_entry_valid+0x98/0xac
> [  120.773730][ T4396] lr : __list_del_entry_valid+0x98/0xac
> [  120.779120][ T4396] sp : ffffffc01e62bb60
> [  120.783126][ T4396] x29: ffffffc01e62bb60 x28: ffffff818ce3a200
> [  120.789126][ T4396] x27: 0000000000000009 x26: 0000000000980000
> [  120.795126][ T4396] x25: ffffffc012431000 x24: ffffff802c6d4e00
> [  120.801125][ T4396] x23: ffffff8005c66f00 x22: ffffffc01183b5b8
> [  120.807125][ T4396] x21: ffffff819df2f100 x20: 0000000000000000
> [  120.813124][ T4396] x19: ffffff802c3f0700 x18: ffffffc01d2cd058
> [  120.819124][ T4396] x17: 0000000000000000 x16: 0000000000000000
> [  120.825124][ T4396] x15: 0000000000000004 x14: 0000000000003fff
> [  120.831123][ T4396] x13: ffffffc012085588 x12: 0000000000000003
> [  120.837123][ T4396] x11: 00000000ffffbfff x10: 0000000000000003
> [  120.843123][ T4396] x9 : 455103d46b329300 x8 : 455103d46b329300
> [  120.849124][ T4396] x7 : 74707572726f6320 x6 : ffffffc0124b8cb5
> [  120.855124][ T4396] x5 : ffffffffffffffff x4 : 0000000000000000
> [  120.861123][ T4396] x3 : ffffffc011cf4f90 x2 : ffffff81fee7b948
> [  120.867122][ T4396] x1 : ffffffc011cf4f90 x0 : 0000000000000054
> [  120.873122][ T4396] Call trace:
> [  120.876259][ T4396]  __list_del_entry_valid+0x98/0xac
> [  120.881304][ T4396]  hid_debug_events_release+0x48/0x12c
> [  120.886617][ T4396]  full_proxy_release+0x50/0xbc
> [  120.891323][ T4396]  __fput+0xdc/0x238
> [  120.895075][ T4396]  ____fput+0x14/0x24
> [  120.898911][ T4396]  task_work_run+0x90/0x148
> [  120.903268][ T4396]  do_exit+0x1bc/0x8a4
> [  120.907193][ T4396]  do_group_exit+0x8c/0xa4
> [  120.911458][ T4396]  get_signal+0x468/0x744
> [  120.915643][ T4396]  do_signal+0x84/0x280
> [  120.919650][ T4396]  do_notify_resume+0xd0/0x218
> [  120.924262][ T4396]  work_pending+0xc/0x3f0
>
> Fixes: cd667ce24796 ("HID: use debugfs for events/reports dumping")
> Signed-off-by: Charles Yi <be286@xxxxxxx>
> ---

This should be v3, but this patch is fine for me content-wise. Thanks
for going over your patch and explaining what you are trying to fix in
further detail.

Reviewed-by: Rahul Rameshbabu <sergeantsagara@xxxxxxxxxxxxxx>