From:   "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To:     Thomas Zimmermann <tzimmermann@suse.de>,
        "deller@gmx.de" <deller@gmx.de>,
        "geert+renesas@glider.be" <geert+renesas@glider.be>,
        "timur@kernel.org" <timur@kernel.org>,
        "rdunlap@infradead.org" <rdunlap@infradead.org>,
        "paulus@samba.org" <paulus@samba.org>,
        "benh@kernel.crashing.org" <benh@kernel.crashing.org>,
        "linux@armlinux.org.uk" <linux@armlinux.org.uk>,
        "pjones@redhat.com" <pjones@redhat.com>,
        "adaplas@gmail.com" <adaplas@gmail.com>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "mbroemme@libmpq.org" <mbroemme@libmpq.org>,
        "thomas@winischhofer.net" <thomas@winischhofer.net>,
        "James.Bottomley@HansenPartnership.com" 
        <James.Bottomley@HansenPartnership.com>,
        "sudipm.mukherjee@gmail.com" <sudipm.mukherjee@gmail.com>,
        "teddy.wang@siliconmotion.com" <teddy.wang@siliconmotion.com>,
        "corbet@lwn.net" <corbet@lwn.net>
CC:     "linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 031/101] fbdev/hyperv_fb: Duplicate video-mode option
 string
Thread-Topic: [PATCH v2 031/101] fbdev/hyperv_fb: Duplicate video-mode option
 string
Thread-Index: AQHZUqEMCW8/QSrXq0ig6mrfyG1yaK72+4hQ
Date:   Sun, 12 Mar 2023 10:51:15 +0000
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References: <20230309160201.5163-1-tzimmermann@suse.de>
 <20230309160201.5163-32-tzimmermann@suse.de>
In-Reply-To: <20230309160201.5163-32-tzimmermann@suse.de>
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From: Thomas Zimmermann <tzimmermann@suse.de> Sent: Thursday, March 9, 2023=
 8:01 AM
>=20
> Assume that the driver does not own the option string or its substrings
> and hence duplicate the option string for the video mode. As the driver
> implements a very simple mode parser in a fairly unstructured way, just
> duplicate the option string and parse the duplicated memory buffer. Free
> the buffer afterwards.
>=20
> Done in preparation of constifying the option string and switching the
> driver to struct option_iter.
>=20
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/video/fbdev/hyperv_fb.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>=20
> diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv=
_fb.c
> index 4a6a3303b6b4..edb0555239c6 100644
> --- a/drivers/video/fbdev/hyperv_fb.c
> +++ b/drivers/video/fbdev/hyperv_fb.c
> @@ -903,17 +903,23 @@ static const struct fb_ops hvfb_ops =3D {
>  static void hvfb_get_option(struct fb_info *info)
>  {
>  	struct hvfb_par *par =3D info->par;
> -	char *opt =3D NULL, *p;
> +	char *options =3D NULL;
> +	char *optbuf, *opt, *p;
>  	uint x =3D 0, y =3D 0;
>=20
> -	if (fb_get_options(KBUILD_MODNAME, &opt) || !opt || !*opt)
> +	if (fb_get_options(KBUILD_MODNAME, &options) || !options || !*options)
>  		return;
>=20
> +	optbuf =3D kstrdup(options, GFP_KERNEL);
> +	if (!optbuf)
> +		return;
> +	opt =3D optbuf;
> +
>  	p =3D strsep(&opt, "x");
>  	if (!*p || kstrtouint(p, 0, &x) ||
>  	    !opt || !*opt || kstrtouint(opt, 0, &y)) {
>  		pr_err("Screen option is invalid: skipped\n");
> -		return;
> +		goto out;
>  	}
>=20
>  	if (x < HVFB_WIDTH_MIN || y < HVFB_HEIGHT_MIN ||
> @@ -922,12 +928,14 @@ static void hvfb_get_option(struct fb_info *info)
>  	    (par->synthvid_version =3D=3D SYNTHVID_VERSION_WIN8 &&
>  	     x * y * screen_depth / 8 > SYNTHVID_FB_SIZE_WIN8)) {
>  		pr_err("Screen resolution option is out of range: skipped\n");
> -		return;
> +		goto out;
>  	}
>=20
>  	screen_width =3D x;
>  	screen_height =3D y;
> -	return;
> +
> +out:
> +	kfree(optbuf);
>  }
>=20
>  /*
> --
> 2.39.2

Reviewed-by: Michael Kelley <mikelley@microsoft.com>