Re: [PATCH] qede: Prevent possible snprintf() truncation by bounding %s string format

[David Laight <david.laight.linux@gmail.com>]

On Wed,  1 Jul 2026 17:47:11 +0300
Baran Tuna <barant@fastmail.com> wrote:

> GCC warning shows that formatted strings may
> exceed the fixed-size destination buffers.
> 
> Bounding the %s string format
> so the maximum formatted output always fits.
> 
> This eliminates the -Wformat-truncation warning.
> 
> Signed-off-by: Baran Tuna <barant@fastmail.com>
> ---
>  drivers/net/ethernet/qlogic/qede/qede_ethtool.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/qlogic/qede/qede_ethtool.c b/drivers/net/ethernet/qlogic/qede/qede_ethtool.c
> index 647f30a16a94..5428f53150a0 100644
> --- a/drivers/net/ethernet/qlogic/qede/qede_ethtool.c
> +++ b/drivers/net/ethernet/qlogic/qede/qede_ethtool.c
> @@ -618,10 +618,10 @@ static void qede_get_drvinfo(struct net_device *ndev,
>  	if ((strlen(storm) + strlen("[storm]")) <
>  	    sizeof(info->version))
>  		snprintf(info->version, sizeof(info->version),
> -			 "[storm %s]", storm);
> +			 "[storm %.16s]", storm);
>  	else
>  		snprintf(info->version, sizeof(info->version),
> -			 "%s", storm);
> +			 "%.16s", storm);

That looks wrong.
The code is using two different formats based on the length
of 'storm' but you are truncating it to the same length in
both cases.
I think this will work:
	if (snprintf(info->version, sizeof(info->version),
		     "[storm %s]", storm) >= sizeof(info->strorm))
		strscpy(info->version, storm);

-- David

>  
>  	if (edev->dev_info.common.mbi_version) {
>  		snprintf(mbi, ETHTOOL_FWVERS_LEN, "%d.%d.%d",
> @@ -632,10 +632,10 @@ static void qede_get_drvinfo(struct net_device *ndev,
>  			 (edev->dev_info.common.mbi_version &
>  			  QED_MBI_VERSION_0_MASK) >> QED_MBI_VERSION_0_OFFSET);
>  		snprintf(info->fw_version, sizeof(info->fw_version),
> -			 "mbi %s [mfw %s]", mbi, mfw);
> +			 "mbi %.10s [mfw %.10s]", mbi, mfw);
>  	} else {
>  		snprintf(info->fw_version, sizeof(info->fw_version),
> -			 "mfw %s", mfw);
> +			 "mfw %.16s", mfw);
>  	}
>  
>  	strscpy(info->bus_info, pci_name(edev->pdev), sizeof(info->bus_info));