Subject: Re: [PATCH v3] soc: aspeed: lpc-snoop: Fix usercopy overflow in snoop_file_read

From: Andrew Jeffery <[email-masked]>
Date: Thu, 28 May 2026 12:09:34 +0930

Hi Karthikeyan,

On Wed, 2026-05-27 at 17:59 +0000, Karthikeyan KS wrote:
> diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c
> index eceeaf8df..ef6697a42 100644
> --- a/drivers/soc/aspeed/aspeed-lpc-snoop.c
> +++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c
> @@ -60,6 +60,7 @@ struct aspeed_lpc_snoop_model_data {
>  
>  struct aspeed_lpc_snoop_channel {
>  	struct kfifo		fifo;
> +	spinlock_t		lock;
>  	wait_queue_head_t	wq;
>  	struct miscdevice	miscdev;
>  };
> @@ -93,7 +94,11 @@ static ssize_t snoop_file_read(struct file *file, char __user *buffer,
>  		if (ret == -ERESTARTSYS)
>  			return -EINTR;
>  	}
> +
> +	spin_lock_irq(&chan->lock);
>  	ret = kfifo_to_user(&chan->fifo, buffer, count, &copied);
> +	spin_unlock_irq(&chan->lock);

This seems inappropriate and I expect is flagged if you compile with
CONFIG_PROVE_LOCKING=y or CONFIG_DEBUG_ATOMIC_SLEEP=y. I suggest both
if you're not already.

Further, I hit conflicts when applying your change on v7.1-rc5. Can you
please ensure you develop, build and test on recent releases.

Thanks,

Andrew