linux-kernel - Re: staging: rtl8723bs mask values in wpa_set_auth

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Date:   Thu, 15 Jul 2021 12:08:47 +0200
From:   Fabio Aiuto <fabioaiuto83@...il.com>
To:     Colin Ian King <colin.king@...onical.com>
Cc:     Quytelda Kahja <quytelda@...alin.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-staging@...ts.linux.dev" <linux-staging@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: staging: rtl8723bs mask values in wpa_set_auth_algs

Hello Colin,

On Fri, Jul 09, 2021 at 03:53:39PM +0100, Colin Ian King wrote:
> Hi,
> 
> Static analysis with Coverity has found an issue introduced by the
> following commit:
> 
> commit 5befa937e8daaebcde81b9423eb93f3ff2e918f7
> Author: Quytelda Kahja <quytelda@...alin.org>
> Date:   Tue Mar 27 01:41:02 2018 -0700
> 
>     staging: rtl8723bs: Fix IEEE80211 authentication algorithm constants.
> 
> The analysis is as follows:
> 
> 347 static int wpa_set_auth_algs(struct net_device *dev, u32 value)
> 348 {
> 349        struct adapter *padapter = rtw_netdev_priv(dev);
> 350        int ret = 0;
> 351
> 352        if ((value & WLAN_AUTH_SHARED_KEY) && (value & WLAN_AUTH_OPEN)) {
> 
> Logically dead code (DEADCODE)
> 
> 353                padapter->securitypriv.ndisencryptstatus =
> Ndis802_11Encryption1Enabled;
> 354                padapter->securitypriv.ndisauthtype =
> Ndis802_11AuthModeAutoSwitch;
> 355                padapter->securitypriv.dot11AuthAlgrthm =
> dot11AuthAlgrthm_Auto;
> 356        } else if (value & WLAN_AUTH_SHARED_KEY)        {
> 357                padapter->securitypriv.ndisencryptstatus =
> Ndis802_11Encryption1Enabled;
> 358
> 359                padapter->securitypriv.ndisauthtype =
> Ndis802_11AuthModeShared;
> 360                padapter->securitypriv.dot11AuthAlgrthm =
> dot11AuthAlgrthm_Shared;
>    dead_error_condition: The condition value & 0U cannot be true.
> 361        } else if (value & WLAN_AUTH_OPEN) {
> 362                /* padapter->securitypriv.ndisencryptstatus =
> Ndis802_11EncryptionDisabled; */
> 
> Logically dead code (DEADCODE)
> 
> 363                if (padapter->securitypriv.ndisauthtype <
> Ndis802_11AuthModeWPAPSK) {
> 364                        padapter->securitypriv.ndisauthtype =
> Ndis802_11AuthModeOpen;
> 365                        padapter->securitypriv.dot11AuthAlgrthm =
> dot11AuthAlgrthm_Open;
> 366                }
> 367        } else {
> 368                ret = -EINVAL;
> 369        }
> 370
> 371        return ret;
> 372
> 373 }
> 
> The deadcode warnings occur because the mask value of WLAN_AUTH_OPEN is
> defined in /include/linux/ieee80211.h as:
> 
> #define WLAN_AUTO_OPEN 0
> 
> and so any value masked with 0 is 0 and hence that part of the if
> statement is always false.
> 
> The original code was using the mask values:
> 
> AUTH_ALG_SHARED_KEY and also AUTH_ALG_OPEN_SYSTEM that are defined as:
> 
> #define AUTH_ALG_OPEN_SYSTEM                   0x1
> #define AUTH_ALG_SHARED_KEY                    0x2

I think that the correct macros are:

/* IW_AUTH_80211_AUTH_ALG values (bit field) */
#define IW_AUTH_ALG_OPEN_SYSTEM 0x00000001
#define IW_AUTH_ALG_SHARED_KEY  0x00000002
#define IW_AUTH_ALG_LEAP        0x00000004

defined in include/uapi/linux/wireless.h

> 
> So this appears to be a regression. I'm not sure the best approach for a
> suitable fix to use the intended macros in ieee80211.h
> 
> Colin
> 
> 
> 
> 

thank you,

fabio