2019-09-27 12:17:46

by Fuqian Huang

Subject: [PATCH] m68k: q40: Fix info-leak in rtc_ioctl

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 <[email protected]>
---
arch/m68k/q40/config.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/m68k/q40/config.c b/arch/m68k/q40/config.c
index e63eb5f06999..f31890078197 100644
--- 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;
--
2.11.0

2019-09-27 12:44:30

by Geert Uytterhoeven

Subject: Re: [PATCH] m68k: q40: Fix info-leak in rtc_ioctl

Hi Fuqian,

On Fri, Sep 27, 2019 at 2:15 PM Fuqian Huang <[email protected]> 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 <[email protected]>

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 <[email protected]>
i.e. will queue for v5.5.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

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