Re: [PATCH net-next] bnx2x: initialize ethtool info->fw_version before use

[Jakub Kicinski]

On Mon, 18 Nov 2019 12:07:53 -0500, Jonathan Toppins wrote:
> If the info->fw_version has garbage in the buffer this can lead to a BUG()
> being generated in strlcat() due to the use of strlen(). Initialize the
> buffer before use.
> 
> The use of a systemtap script can demonstrate the problem by injecting
> garbage into fw_version:


> @@ -1111,6 +1111,8 @@ static void bnx2x_get_drvinfo(struct net_device *dev,
>  	int ext_dev_info_offset;
>  	u32 mbi;
>  
> +	info->fw_version[0] = 0;
> +
>  	strlcpy(info->driver, DRV_MODULE_NAME, sizeof(info->driver));
>  	strlcpy(info->version, DRV_MODULE_VERSION, sizeof(info->version));

I don't know systemtap, so it's very unclear what you're trying to fix
here. Setting random fields of info to 0 seems pointless as the entire
structure is zeroed before the call in ethtool_get_drvinfo().

Please explain.