Re: [PATCH v9] staging: rtl8723bs: fix WEP length underflow and OOB read in OnAuth()

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, May 21, 2026 at 03:03:24PM +0200, Alexandru Hossu wrote:
> OnAuth() has two bugs in the shared-key authentication path.
> 
> When the Privacy bit is set, rtw_wep_decrypt() is called without
> verifying that the frame is long enough to contain a valid WEP IV and
> ICV.  Inside rtw_wep_decrypt(), length is computed as:
> 
>     length = len - WLAN_HDR_A3_LEN - iv_len
> 
> and then passed as (length - 4) to crc32_le().  If len is less than
> WLAN_HDR_A3_LEN + iv_len + icv_len (32 bytes), length - 4 is negative
> and, after the implicit cast to size_t, causes crc32_le() to read far
> beyond the frame buffer.  Add a minimum length check before accessing
> the IV field and calling the decryption path.
> 
> When processing a seq=3 response, rtw_get_ie() stores the Challenge
> Text IE length in ie_len, but the subsequent memcmp() always reads 128
> bytes regardless of ie_len.  IEEE 802.11 mandates a challenge text of
> exactly 128 bytes; reject any IE whose length field differs, matching
> the check already applied to OnAuthClient().
> 
> Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Alexandru Hossu <hossu.alexandru@gmail.com>
> ---
> v9: add WLAN_HDR_A3_LEN guard and WEP minimum length check before
>     iv[3] access and rtw_wep_decrypt(); tighten ie_len check from
>     <= 0 to != 128 to reject under-size challenge IEs
> 
>  drivers/staging/rtl8723bs/core/rtw_mlme_ext.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
> index 68ce422305ed..8575b7bd6d84 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
> @@ -687,6 +687,9 @@ unsigned int OnAuth(struct adapter *padapter, union recv_frame *precv_frame)
>  	if ((pmlmeinfo->state&0x03) != WIFI_FW_AP_STATE)
>  		return _FAIL;
>  
> +	if (len < WLAN_HDR_A3_LEN)
> +		return _FAIL;
> +
>  	sa = GetAddr2Ptr(pframe);
>  
>  	auth_mode = psecuritypriv->dot11AuthAlgrthm;
> @@ -698,6 +701,9 @@ unsigned int OnAuth(struct adapter *padapter, union recv_frame *precv_frame)
>  		prxattrib->hdrlen = WLAN_HDR_A3_LEN;
>  		prxattrib->encrypt = _WEP40_;
>  
> +		if (len < WLAN_HDR_A3_LEN + 8)
> +			return _FAIL;
> +
>  		iv = pframe+prxattrib->hdrlen;
>  		prxattrib->key_index = ((iv[3]>>6)&0x3);
>  
> @@ -802,7 +808,7 @@ unsigned int OnAuth(struct adapter *padapter, union recv_frame *precv_frame)
>  			p = rtw_get_ie(pframe + WLAN_HDR_A3_LEN + 4 + _AUTH_IE_OFFSET_, WLAN_EID_CHALLENGE, (int *)&ie_len,
>  					len - WLAN_HDR_A3_LEN - _AUTH_IE_OFFSET_ - 4);
>  
> -			if (!p || ie_len <= 0) {
> +			if (!p || ie_len != 128) {
>  				status = WLAN_STATUS_CHALLENGE_FAIL;
>  				goto auth_fail;
>  			}
> -- 
> 2.54.0
> 
> 

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)
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  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/process/submitting-patches.rst for what
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