Re: [PATCH] kni: fix build with gcc 8.1

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 19 Jun 2018 13:08:55 +0100
Ferruh Yigit <ferruh.yigit@intel.com> wrote:

> Error observed when CONFIG_RTE_KNI_KMOD_ETHTOOL config option is
> enabled.
> 
> build error:
> In function ‘strncpy’,
>     inlined from ‘igb_get_drvinfo’ at
>     .../dpdk/build/build/kernel/linux/kni/igb_ethtool.c:814:2:
>     .../include/linux/string.h:246:9: error: ‘__builtin_strncpy’ output
>     may be truncated copying 31 bytes from a string of length 42
>     [-Werror=stringop-truncation]
>       return __builtin_strncpy(p, q, size);
>                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Fixed by reducing the adapter->fw_version size and adjusting strncpy
> limit size.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> ---
>  kernel/linux/kni/ethtool/igb/igb.h         | 2 +-
>  kernel/linux/kni/ethtool/igb/igb_ethtool.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/linux/kni/ethtool/igb/igb.h b/kernel/linux/kni/ethtool/igb/igb.h
> index 8aa2a3088..5e798ae83 100644
> --- a/kernel/linux/kni/ethtool/igb/igb.h
> +++ b/kernel/linux/kni/ethtool/igb/igb.h
> @@ -592,7 +592,7 @@ struct igb_adapter {
>  	int int_mode;
>  	u32 rss_queues;
>  	u32 vmdq_pools;
> -	char fw_version[43];
> +	char fw_version[32];

Use ETHTOOL_FWVERS_LEN?

>  	u32 wvbr;
>  	struct igb_mac_addr *mac_table;
>  #ifdef CONFIG_IGB_VMDQ_NETDEV
> diff --git a/kernel/linux/kni/ethtool/igb/igb_ethtool.c b/kernel/linux/kni/ethtool/igb/igb_ethtool.c
> index 064528bcf..0b8b25ff1 100644
> --- a/kernel/linux/kni/ethtool/igb/igb_ethtool.c
> +++ b/kernel/linux/kni/ethtool/igb/igb_ethtool.c
> @@ -812,7 +812,7 @@ static void igb_get_drvinfo(struct net_device *netdev,
>  	strncpy(drvinfo->version, igb_driver_version, sizeof(drvinfo->version) - 1);
>  
>  	strncpy(drvinfo->fw_version, adapter->fw_version,
> -		sizeof(drvinfo->fw_version) - 1);
> +		sizeof(drvinfo->fw_version));

Why not:
	strlcpy(drvinfo->fw_version, adapter->fw_version,
		sizeof(drvinfo->fw_version));