linux-kernel - Re: [PATCH v2] wifi: wl1251: replace deprecated strncpy with strscpy

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Message-ID: <202310182025.8A48543E6@keescook>
Date:   Wed, 18 Oct 2023 20:25:40 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Kalle Valo <kvalo@...nel.org>, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] wifi: wl1251: replace deprecated strncpy with strscpy

On Wed, Oct 18, 2023 at 09:15:23PM +0000, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
> 
> Based on other assignments of similar fw_version fields we can see that
> NUL-termination is required but not NUL-padding:
> ethernet/intel/ixgbe/ixgbe_ethtool.c
> 1111:   strscpy(drvinfo->fw_version, adapter->eeprom_id,
> 1112:           sizeof(drvinfo->fw_version));
> 
> ethernet/intel/igc/igc_ethtool.c
> 147:    scnprintf(adapter->fw_version,
> 148:              sizeof(adapter->fw_version),
> 153:    strscpy(drvinfo->fw_version, adapter->fw_version,
> 154:            sizeof(drvinfo->fw_version));
> 
> wireless/broadcom/brcm80211/brcmfmac/core.c
> 569:    strscpy(info->fw_version, drvr->fwver, sizeof(info->fw_version));
> 
> wireless/broadcom/brcm80211/brcmsmac/main.c
> 7867:           snprintf(wlc->wiphy->fw_version,
> 7868:                    sizeof(wlc->wiphy->fw_version), "%u.%u", rev, patch);
> 
> wireless/broadcom/b43legacy/main.c
> 1765:   snprintf(wiphy->fw_version, sizeof(wiphy->fw_version), "%u.%u",
> 
> wireless/broadcom/b43/main.c
> 2730:   snprintf(wiphy->fw_version, sizeof(wiphy->fw_version), "%u.%u",
> 
> wireless/intel/iwlwifi/dvm/main.c
> 1465:   snprintf(priv->hw->wiphy->fw_version,
> 1466:            sizeof(priv->hw->wiphy->fw_version),
> 
> wireless/intel/ipw2x00/ipw2100.c
> 5905:   snprintf(info->fw_version, sizeof(info->fw_version), "%s:%d:%s",
> 
> A suitable replacement is `strscpy` due to the fact that it guarantees
> NUL-termination on the destination buffer without unnecessarily
> NUL-padding.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

Yup, looks like a clean replacement.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook