linux-kernel - Re: [PATCH v2 4/5] staging: rtl8723bs: fix out-of-bounds check in rtw_restruct_wmm

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Message-ID: <2026012925-emblaze-barrel-46fc@gregkh>
Date: Thu, 29 Jan 2026 15:13:18 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Luka Gejak <lukagejak5@...il.com>
Cc: straube.linux@...il.com, dan.carpenter@...aro.org,
	linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/5] staging: rtl8723bs: fix out-of-bounds check in
 rtw_restruct_wmm_ie

On Thu, Jan 29, 2026 at 02:23:51PM +0100, Luka Gejak wrote:
> Add a length check before accessing the OUI in WMM
> IE to prevent potential out-of-bounds reads.

Is this really a bugfix?  if so, it needs to go first, and be tagged for
stable trees.

> Use memcmp() for better readability.
> 
> Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
> 
> Signed-off-by: Luka Gejak <lukagejak5@...il.com>
> ---
>  drivers/staging/rtl8723bs/core/rtw_mlme.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
> index c4f58106b3bd..18a70879f78f 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
> @@ -2000,7 +2000,8 @@ int rtw_restruct_wmm_ie(struct adapter *adapter, u8 *in_ie, u8 *out_ie, uint in_
>  	while (i < in_len) {
>  		ielength = initial_out_len;
>  
> -		if (in_ie[i] == 0xDD && in_ie[i+2] == 0x00 && in_ie[i+3] == 0x50  && in_ie[i+4] == 0xF2 && in_ie[i+5] == 0x02 && i+5 < in_len) { /* WMM element ID and OUI */
> +		if (i + 5 < in_len && in_ie[i] == 0xDD &&
> +		!memcmp(&in_ie[i + 2], "\x00\x50\xf2\x02", 4)) {

Very odd indentation :(

Also, why invert the i+5 check?  And the memcmp check is now messier
than the original.

And is that where you are saying this is a security fix?  If so, it's
just a read, not a write, so what is the security issue?

thanks,

greg k-h