linux-kernel - Re: [PATCH] staging: rtl8192e: Fix possible buffer overflow in _rtl92e_wx_set

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Date:   Fri, 26 Feb 2021 13:06:46 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Lee Gibson <leegib@...il.com>
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: rtl8192e: Fix possible buffer overflow in
 _rtl92e_wx_set_scan

On Fri, Feb 26, 2021 at 11:48:29AM +0000, Lee Gibson wrote:
> Function _rtl92e_wx_set_scan calls memcpy without checking the length.
> A user could control that length and trigger a buffer overflow.
> Fix by checking the length is within the maximum allowed size.
> 
> Signed-off-by: Lee Gibson <leegib@...il.com>
> ---
>  drivers/staging/rtl8192e/rtl8192e/rtl_wx.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c b/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
> index 16bcee13f64b..2acc4f314732 100644
> --- a/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
> +++ b/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
> @@ -406,6 +406,9 @@ static int _rtl92e_wx_set_scan(struct net_device *dev,
>  		struct iw_scan_req *req = (struct iw_scan_req *)b;
>  
>  		if (req->essid_len) {
> +			if (req->essid_len > IW_ESSID_MAX_SIZE)
> +				req->essid_len = IW_ESSID_MAX_SIZE;
> +

How about using the "pattern" the other wireless drivers use of:

		int len = min((int)req->essid_len, IW_ESSID_MAX_SIZE);

instead?

thanks,

greg k-h