linux-kernel - Re: [PATCH] m68k: q40: Fix info-leak in rtc

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Message-ID: <CAMuHMdVpHUe5UC2RpZp40=0UeT0jVqH-PCS3pmoZTVkdEnocsg@mail.gmail.com>
Date:   Fri, 27 Sep 2019 14:43:19 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Fuqian Huang <huangfq.daxian@...il.com>
Cc:     linux-m68k <linux-m68k@...ts.linux-m68k.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] m68k: q40: Fix info-leak in rtc_ioctl

Hi Fuqian,

On Fri, Sep 27, 2019 at 2:15 PM Fuqian Huang <huangfq.daxian@...il.com> wrote:
> When the option is RTC_PLL_GET, pll will be copied to userland
> via copy_to_user. pll is initialized using mach_get_rtc_pll indirect
> call and mach_get_rtc_pll is only assigned with function
> q40_get_rtc_pll in arch/m68k/q40/config.c.
> In function q40_get_rtc_pll, the field pll_ctrl is not initialized.
> This will leak uninitialized stack content to userland.
> Fix this by zeroing the uninitialized field.
>
> Signed-off-by: Fuqian Huang <huangfq.daxian@...il.com>

Thanks for your patch!

> --- a/arch/m68k/q40/config.c
> +++ b/arch/m68k/q40/config.c
> @@ -264,6 +264,7 @@ static int q40_get_rtc_pll(struct rtc_pll_info *pll)
>  {
>         int tmp = Q40_RTC_CTRL;
>
> +       pll->pll_ctrl = 0;
>         pll->pll_value = tmp & Q40_RTC_PLL_MASK;
>         if (tmp & Q40_RTC_PLL_SIGN)
>                 pll->pll_value = -pll->pll_value;

Nice catch!

Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
i.e. will queue for v5.5.

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