linux-kernel - Re: [PATCH v2 061/101] fbdev/ps3fb: Duplicate video-mode option string

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 10 Mar 2023 09:18:14 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     deller@....de, timur@...nel.org, rdunlap@...radead.org,
        paulus@...ba.org, benh@...nel.crashing.org, linux@...linux.org.uk,
        pjones@...hat.com, adaplas@...il.com, s.hauer@...gutronix.de,
        shawnguo@...nel.org, mbroemme@...mpq.org, thomas@...ischhofer.net,
        James.Bottomley@...senpartnership.com, sudipm.mukherjee@...il.com,
        teddy.wang@...iconmotion.com, corbet@....net,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 061/101] fbdev/ps3fb: Duplicate video-mode option string

Hi Thomas,

On Thu, Mar 9, 2023 at 5:02 PM Thomas Zimmermann <tzimmermann@...e.de> wrote:
> Assume that the driver does not own the option string or its substrings
> and hence duplicate the option string for the video mode. Allocate the
> copy's memory with kstrdup() and free it in the module's exit function.
>
> Done in preparation of switching the driver to struct option_iter and
> constifying the option string.
>
> v2:
>         * replace static memory with kstrdup()/kfree() (Geert)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>

Thanks for the upodate!

> --- a/drivers/video/fbdev/ps3fb.c
> +++ b/drivers/video/fbdev/ps3fb.c
> @@ -260,6 +260,7 @@ static const struct fb_videomode ps3fb_modedb[] = {
>  static int ps3fb_mode;
>  module_param(ps3fb_mode, int, 0);
>
> +static char *mode_option_buf;

Do you really need this variable? It contains the same value
as mode_option below.
This is a common pattern in several patches.

>  static char *mode_option;
>
>  static int ps3fb_cmp_mode(const struct fb_videomode *vmode,
> @@ -1276,8 +1277,11 @@ static int __init ps3fb_setup(void)
>                         continue;
>                 if (!strncmp(this_opt, "mode:", 5))
>                         ps3fb_mode = simple_strtoul(this_opt + 5, NULL, 0);
> -               else
> -                       mode_option = this_opt;
> +               else {
> +                       kfree(mode_option_buf);
> +                       mode_option_buf = kstrdup(this_opt, GFP_KERNEL); // ignore errors
> +                       mode_option = mode_option_buf;
> +               }
>         }
>         return 0;
>  }
> @@ -1294,6 +1298,7 @@ static void __exit ps3fb_exit(void)
>  {
>         pr_debug(" -> %s:%d\n", __func__, __LINE__);
>         ps3_system_bus_driver_unregister(&ps3fb_driver);
> +       kfree(mode_option_buf);
>         pr_debug(" <- %s:%d\n", __func__, __LINE__);
>  }

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds