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Date:   Thu, 21 Nov 2019 11:35:04 +0100
From:   Pavel Machek <pavel@denx.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Mitch Williams <mitch.a.williams@intel.com>,
        Andrew Bowers <andrewx.bowers@intel.com>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.19 079/422] i40e: use correct length for strncpy
Message-ID: <20191121103504.GC26882@amd>
References: <20191119051400.261610025@linuxfoundation.org>
 <20191119051404.622986351@linuxfoundation.org>
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Hi!

> From: Mitch Williams <mitch.a.williams@intel.com>
>=20
> [ Upstream commit 7eb74ff891b4e94b8bac48f648a21e4b94ddee64 ]
>=20
> Caught by GCC 8. When we provide a length for strncpy, we should not
> include the terminating null. So we must tell it one less than the size
> of the destination buffer.

> +++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> @@ -694,7 +694,8 @@ static long i40e_ptp_create_clock(struct i40e_pf *pf)
>  	if (!IS_ERR_OR_NULL(pf->ptp_clock))
>  		return 0;
> =20
> -	strncpy(pf->ptp_caps.name, i40e_driver_name, sizeof(pf->ptp_caps.name));
> +	strncpy(pf->ptp_caps.name, i40e_driver_name,
> +		sizeof(pf->ptp_caps.name) - 1);
>  	pf->ptp_caps.owner =3D THIS_MODULE;
>  	pf->ptp_caps.max_adj =3D 999999999;
>  	pf->ptp_caps.n_ext_ts =3D 0;

So... pf is allocated with kzalloc, which will provide the null
termination... so the code is okay.

On the other hand, the =3D 0 below is unneeded by the same logic, so
this is a bit confusing.

Best regards,
								Pavel
--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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