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From:   Lukasz Stelmach <l.stelmach@samsung.com>
To:     Justin Stitt <justinstitt@google.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] net: ax88796c: replace deprecated strncpy with strscpy
Date:   Thu, 05 Oct 2023 10:40:46 +0200
In-Reply-To: <20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-v1-1-6fafdc38b170@google.com>
        (Justin Stitt's message of "Thu, 05 Oct 2023 01:06:26 +0000")
Message-ID: <oypijd34yp5unl.fsf%l.stelmach@samsung.com>
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References: <20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-v1-1-6fafdc38b170@google.com>
        <CGME20231005084046eucas1p1a8dcb84361cc0ef1242768ecc1a96664@eucas1p1.samsung.com>
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It was <2023-10-05 czw 01:06>, when 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.
>
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
>
> It should be noted that there doesn't currently exist a bug here as
> DRV_NAME is a small string literal which means no overread bugs are
> present.
>
> Also to note, other ethernet drivers are using strscpy in a similar
> pattern:
> |       dec/tulip/tulip_core.c
> |       861:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/ax88796.c
> |       582:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       dec/tulip/dmfe.c
> |       1077:   strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/etherh.c
> |       558:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strn=
cpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.h=
tml [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
> Note: build-tested only.
> ---
>  drivers/net/ethernet/asix/ax88796c_ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Reviewed-by: Lukasz Stelmach <l.stelmach@samsung.com>

> diff --git a/drivers/net/ethernet/asix/ax88796c_ioctl.c b/drivers/net/eth=
ernet/asix/ax88796c_ioctl.c
> index 916ae380a004..7d2fe2e5af92 100644
> --- a/drivers/net/ethernet/asix/ax88796c_ioctl.c
> +++ b/drivers/net/ethernet/asix/ax88796c_ioctl.c
> @@ -24,7 +24,7 @@ static void
>  ax88796c_get_drvinfo(struct net_device *ndev, struct ethtool_drvinfo *in=
fo)
>  {
>  	/* Inherit standard device info */
> -	strncpy(info->driver, DRV_NAME, sizeof(info->driver));
> +	strscpy(info->driver, DRV_NAME, sizeof(info->driver));
>  }
>=20=20
>  static u32 ax88796c_get_msglevel(struct net_device *ndev)
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-56=
af20b7d992
>
> Best regards,
> --
> Justin Stitt <justinstitt@google.com>
>
>
>

=2D-=20
=C5=81ukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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