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Date: Mon, 8 Apr 2024 20:35:09 +0000
From: Justin Stitt <justinstitt@google.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
	Nathan Chancellor <nathan@kernel.org>, Dan Carpenter <dan.carpenter@linaro.org>, 
	Arnd Bergmann <arnd@arndb.de>, Nick Desaulniers <ndesaulniers@google.com>, 
	Bill Wendling <morbo@google.com>, Franziska Naepelt <franziska.naepelt@googlemail.com>, 
	Johannes Berg <johannes.berg@intel.com>, Jeff Johnson <quic_jjohnson@quicinc.com>, 
	Aloka Dixit <quic_alokad@quicinc.com>, Erick Archer <erick.archer@gmx.com>, 
	Yang Yingliang <yangyingliang@huawei.com>, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, 
	llvm@lists.linux.dev
Subject: Re: [PATCH 2/3] [v2] staging: rtl8723bs: convert strncpy to strscpy
Message-ID: <5tivf4xqef52ivneq6ucs2au2ld62ruwmjddhrhrgnltr3q3vj@iykmv323noqq>
References: <20240408194821.3183462-1-arnd@kernel.org>
 <20240408194821.3183462-2-arnd@kernel.org>
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In-Reply-To: <20240408194821.3183462-2-arnd@kernel.org>

Hi,

On Mon, Apr 08, 2024 at 09:48:10PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> gcc-9 complains about a possibly unterminated string in the strncpy() destination:
> 
> In function 'rtw_cfg80211_add_monitor_if',
>     inlined from 'cfg80211_rtw_add_virtual_intf' at drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c:2209:9:
> drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c:2146:2: error: 'strncpy' specified bound 16 equals destination size [-Werror=stringop-truncation]
>  2146 |  strncpy(mon_ndev->name, name, IFNAMSIZ);
>       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> This one is a false-positive because of the explicit termination in the following
> line, and recent versions of clang and gcc no longer warn about this.
> 
> Interestingly, the other strncpy() in this file is missing a termination but
> does not produce a warning, possibly because of the type confusion and the
> cast between u8 and char.
> 
> Change both strncpy() instances to strscpy(), which avoids the warning as well
> as the possibly missing termination. No additional padding is needed here.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Helps with: https://github.com/KSPP/linux/issues/90

and for the bots...
Link: https://github.com/KSPP/linux/issues/90

Reviewed-by: Justin Stitt <justinstitt@google.com>

> ---
> v2:
>   use the two-argument version of strscpy(), which is simpler for the constant
>   size destination. Add the third instance in this driver as well.
> ---
>  drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 5 ++---
>  drivers/staging/rtl8723bs/os_dep/os_intfs.c       | 2 +-
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> index 65a450fcdce7..3fe27ee75b47 100644
> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> @@ -884,7 +884,7 @@ static int cfg80211_rtw_add_key(struct wiphy *wiphy, struct net_device *ndev,
>  		goto addkey_end;
>  	}
>  
> -	strncpy((char *)param->u.crypt.alg, alg_name, IEEE_CRYPT_ALG_NAME_LEN);
> +	strscpy(param->u.crypt.alg, alg_name);
>  
>  	if (!mac_addr || is_broadcast_ether_addr(mac_addr))
>  		param->u.crypt.set_tx = 0; /* for wpa/wpa2 group key */
> @@ -2143,8 +2143,7 @@ static int rtw_cfg80211_add_monitor_if(struct adapter *padapter, char *name, str
>  	}
>  
>  	mon_ndev->type = ARPHRD_IEEE80211_RADIOTAP;
> -	strncpy(mon_ndev->name, name, IFNAMSIZ);
> -	mon_ndev->name[IFNAMSIZ - 1] = 0;
> +	strscpy(mon_ndev->name, name);
>  	mon_ndev->needs_free_netdev = true;
>  	mon_ndev->priv_destructor = rtw_ndev_destructor;
>  
> diff --git a/drivers/staging/rtl8723bs/os_dep/os_intfs.c b/drivers/staging/rtl8723bs/os_dep/os_intfs.c
> index 68bba3c0e757..55d0140cd543 100644
> --- a/drivers/staging/rtl8723bs/os_dep/os_intfs.c
> +++ b/drivers/staging/rtl8723bs/os_dep/os_intfs.c
> @@ -415,7 +415,7 @@ static int rtw_ndev_init(struct net_device *dev)
>  	struct adapter *adapter = rtw_netdev_priv(dev);
>  
>  	netdev_dbg(dev, FUNC_ADPT_FMT "\n", FUNC_ADPT_ARG(adapter));
> -	strncpy(adapter->old_ifname, dev->name, IFNAMSIZ);
> +	strscpy(adapter->old_ifname, dev->name);
>  
>  	return 0;
>  }
> -- 
> 2.39.2
> 
>

Thanks
Justin