linux-kernel - Re: [PATCH] wifi: ath6kl: Check that the read operation returns a data length of 0

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Message-ID: <2024082507-clay-riveting-16f3@gregkh>
Date: Sun, 25 Aug 2024 09:25:37 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Edward Adam Davis <eadavis@...com>
Cc: syzbot+92c6dd14aaa230be6855@...kaller.appspotmail.com, kvalo@...nel.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] wifi: ath6kl: Check that the read operation returns a
 data length of 0

On Sun, Aug 25, 2024 at 03:10:03PM +0800, Edward Adam Davis wrote:
> If the data length returned by the device is 0, the read operation
> should be considered a failure.
> 
> Reported-and-tested-by: syzbot+92c6dd14aaa230be6855@...kaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@...com>
> ---
>  drivers/net/wireless/ath/ath6kl/usb.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
> index 5220809841a6..2a89bab81b24 100644
> --- a/drivers/net/wireless/ath/ath6kl/usb.c
> +++ b/drivers/net/wireless/ath/ath6kl/usb.c
> @@ -1034,6 +1034,9 @@ static int ath6kl_usb_bmi_read(struct ath6kl *ar, u8 *buf, u32 len)
>  		ath6kl_err("Unable to read the bmi data from the device: %d\n",
>  			   ret);
>  		return ret;
> +	} else {
> +		ath6kl_err("Actual read the bmi data length is 0 from the device\n");
> +		return -EIO;

Close, but not quite there.  ath6kl_usb_submit_ctrl_in() needs to verify
that the actual amount of data was read that was asked for.  If a short
read happens (or a long one), then an error needs to propagate out, not
just 0.  See the "note:" line in that function for what needs to be
properly checked.

hope this helps,

greg k-h