Re: [PATCH v2] staging: rtl8723bs: fix out-of-bounds reads in IE parsing functions

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Apr 05, 2026 at 01:00:24AM +0100, Delene Tchio Romuald wrote:
> The IE parsing loops in rtw_get_wapi_ie(), rtw_get_sec_ie(), and
> rtw_get_wps_ie() check only that the element ID byte is within bounds
> (cnt < in_len), but then immediately access the length byte at
> in_ie[cnt+1] and data bytes at in_ie[cnt+2] and beyond without
> verifying that these offsets are within the buffer.
> 
> A malicious access point can send beacon or probe response frames with
> truncated Information Elements, triggering out-of-bounds reads on
> kernel heap memory. No authentication is required.
> 
> Add two bounds checks to each function:
>  - Ensure at least 2 bytes remain for the IE header (cnt + 1 < in_len)
>  - Validate the full IE fits in the buffer before accessing its data
>    (cnt + 2 + ie_len <= in_len)
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Delene Tchio Romuald <delenetchior1@gmail.com>
> ---
>  drivers/staging/rtl8723bs/core/rtw_ieee80211.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/rtl8723bs/core/rtw_ieee80211.c b/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
> index 72b7f731d..e0fed3f42 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
> @@ -582,9 +582,12 @@ int rtw_get_wapi_ie(u8 *in_ie, uint in_len, u8 *wapi_ie, u16 *wapi_len)
>  
>  	cnt = (_TIMESTAMP_ + _BEACON_ITERVAL_ + _CAPABILITY_);
>  
> -	while (cnt < in_len) {
> +	while (cnt + 1 < in_len) {
>  		authmode = in_ie[cnt];
>  
> +		if (cnt + 2 + in_ie[cnt + 1] > in_len)
> +			break;
> +
>  		if (authmode == WLAN_EID_BSS_AC_ACCESS_DELAY &&
>  		    (!memcmp(&in_ie[cnt + 6], wapi_oui1, 4) ||
>  		     !memcmp(&in_ie[cnt + 6], wapi_oui2, 4))) {
> @@ -615,9 +618,12 @@ void rtw_get_sec_ie(u8 *in_ie, uint in_len, u8 *rsn_ie, u16 *rsn_len, u8 *wpa_ie
>  
>  	cnt = (_TIMESTAMP_ + _BEACON_ITERVAL_ + _CAPABILITY_);
>  
> -	while (cnt < in_len) {
> +	while (cnt + 1 < in_len) {
>  		authmode = in_ie[cnt];
>  
> +		if (cnt + 2 + in_ie[cnt + 1] > in_len)
> +			break;
> +
>  		if ((authmode == WLAN_EID_VENDOR_SPECIFIC) &&
>  		    (!memcmp(&in_ie[cnt + 2], &wpa_oui[0], 4))) {
>  			if (wpa_ie)
> @@ -658,9 +664,12 @@ u8 *rtw_get_wps_ie(u8 *in_ie, uint in_len, u8 *wps_ie, uint *wps_ielen)
>  
>  	cnt = 0;
>  
> -	while (cnt < in_len) {
> +	while (cnt + 1 < in_len) {
>  		eid = in_ie[cnt];
>  
> +		if (cnt + 2 + in_ie[cnt + 1] > in_len)
> +			break;
> +
>  		if ((eid == WLAN_EID_VENDOR_SPECIFIC) && (!memcmp(&in_ie[cnt + 2], wps_oui, 4))) {
>  			wpsie_ptr = &in_ie[cnt];
>  
> -- 
> 2.43.0
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/process/submitting-patches.rst for what
  needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot