Re: usb: gadget: function: add spinlock for rndis response list

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Feb 18, 2022 at 02:29:55PM +0900, Daehwan Jung wrote:
> There's no lock for rndis response list. It could cause list corruption
> if two different list_add at the same time like below.
> It's better to add in rndis_add_response / rndis_free_response
> / rndis_get_next_response to prevent any race condition on response list.
> 
> [  361.894299] [1:   irq/191-dwc3:16979] list_add corruption.
> next->prev should be prev (ffffff80651764d0),
> but was ffffff883dc36f80. (next=ffffff80651764d0).
> 
> [  361.904380] [1:   irq/191-dwc3:16979] Call trace:
> [  361.904391] [1:   irq/191-dwc3:16979]  __list_add_valid+0x74/0x90
> [  361.904401] [1:   irq/191-dwc3:16979]  rndis_msg_parser+0x168/0x8c0
> [  361.904409] [1:   irq/191-dwc3:16979]  rndis_command_complete+0x24/0x84
> [  361.904417] [1:   irq/191-dwc3:16979]  usb_gadget_giveback_request+0x20/0xe4
> [  361.904426] [1:   irq/191-dwc3:16979]  dwc3_gadget_giveback+0x44/0x60
> [  361.904434] [1:   irq/191-dwc3:16979]  dwc3_ep0_complete_data+0x1e8/0x3a0
> [  361.904442] [1:   irq/191-dwc3:16979]  dwc3_ep0_interrupt+0x29c/0x3dc
> [  361.904450] [1:   irq/191-dwc3:16979]  dwc3_process_event_entry+0x78/0x6cc
> [  361.904457] [1:   irq/191-dwc3:16979]  dwc3_process_event_buf+0xa0/0x1ec
> [  361.904465] [1:   irq/191-dwc3:16979]  dwc3_thread_interrupt+0x34/0x5c
> 
> Fixes: f6281af9d62e ("usb: gadget: rndis: use list_for_each_entry_safe")
> Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
> ---
>  drivers/usb/gadget/function/rndis.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
> index b7ccf1803656..b4d58324e2d2 100644
> --- a/drivers/usb/gadget/function/rndis.c
> +++ b/drivers/usb/gadget/function/rndis.c
> @@ -1011,16 +1011,21 @@ void rndis_add_hdr(struct sk_buff *skb)
>  }
>  EXPORT_SYMBOL_GPL(rndis_add_hdr);
>  
> +/* add spinlock to prevent race condition for rndis response list */
> +static DEFINE_SPINLOCK(resp_lock);

Shouldn't this be one lock per rndis_params structure, and not a global
one for the whole driver?

thanks,

greg k-h