Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.33 as permitted sender) client-ip=23.128.96.33;
Message-ID: <00fba033910961bac96dabe9d7e0435342fd021d.camel@redhat.com>
Subject: Re: [PATCH] drm/nouveau/core: refactor deprecated strncpy
From:   Lyude Paul <lyude@redhat.com>
To:     Justin Stitt <justinstitt@google.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        Karol Herbst <kherbst@redhat.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>
Cc:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Date:   Fri, 15 Sep 2023 13:33:32 -0400
In-Reply-To: <20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-v1-1-3aeae46c032f@google.com>
References: <20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-v1-1-3aeae46c032f@google.com>
Organization: Red Hat Inc.
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) 
MIME-Version: 1.0
Precedence: bulk

Eek, I didn't realize how many instances of this we had. Thanks for doing t=
his
:)

Reviewed-by: Lyude Paul <lyude@redhat.com>

On Thu, 2023-09-14 at 21:40 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1]=
.
>=20
> We should prefer more robust and less ambiguous string interfaces.
>=20
> A suitable replacement is `strscpy` [2] due to the fact that it guarantee=
s
> NUL-termination on the destination buffer without unnecessarily NUL-paddi=
ng.
>=20
> There is likely no bug in the current implementation due to the safeguard=
:
> > 	cname[sizeof(cname) - 1] =3D '\0';
> ... however we can provide simpler and easier to understand code using
> the newer (and recommended) `strscpy` api.
>=20
> 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>
> ---
>  drivers/gpu/drm/nouveau/nvkm/core/firmware.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>=20
> diff --git a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c b/drivers/gpu/d=
rm/nouveau/nvkm/core/firmware.c
> index 91fb494d4009..374212da9e95 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c
> @@ -79,8 +79,7 @@ nvkm_firmware_get(const struct nvkm_subdev *subdev, con=
st char *fwname, int ver,
>  	int i;
> =20
>  	/* Convert device name to lowercase */
> -	strncpy(cname, device->chip->name, sizeof(cname));
> -	cname[sizeof(cname) - 1] =3D '\0';
> +	strscpy(cname, device->chip->name, sizeof(cname));
>  	i =3D strlen(cname);
>  	while (i) {
>  		--i;
>=20
> ---
> base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec
> change-id: 20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-=
791223838b72
>=20
> Best regards,
> --
> Justin Stitt <justinstitt@google.com>
>=20

--=20
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat