[PATCH] PM / OPP: Use snprintf() instead of sprintf()

[PATCH] PM / OPP: Use snprintf() instead of sprintf()

[Viresh Kumar]

sprintf() can access memory outside of the range of the character array,
and is risky in some situations. The driver specified prop_name string
can be longer than NAME_MAX here (only an attacker will do that though)
and so blindly copying it into the character array of size NAME_MAX
isn't safe. Instead we must use snprintf() here.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/base/power/opp/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index cd230c63aee6..cf351d3dab1c 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -808,7 +808,8 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
 
 	/* Search for "opp-microvolt-<name>" */
 	if (dev_opp->prop_name) {
-		sprintf(name, "opp-microvolt-%s", dev_opp->prop_name);
+		snprintf(name, sizeof(name), "opp-microvolt-%s",
+			 dev_opp->prop_name);
 		prop = of_find_property(opp->np, name, NULL);
 	}
 
@@ -849,7 +850,8 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
 	/* Search for "opp-microamp-<name>" */
 	prop = NULL;
 	if (dev_opp->prop_name) {
-		sprintf(name, "opp-microamp-%s", dev_opp->prop_name);
+		snprintf(name, sizeof(name), "opp-microamp-%s",
+			 dev_opp->prop_name);
 		prop = of_find_property(opp->np, name, NULL);
 	}
 
-- 
2.7.0.rc1.186.g94414c4

Re: [PATCH] PM / OPP: Use snprintf() instead of sprintf()

[Geert Uytterhoeven]

On Tue, Jan 5, 2016 at 11:45 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> sprintf() can access memory outside of the range of the character array,
> and is risky in some situations. The driver specified prop_name string
> can be longer than NAME_MAX here (only an attacker will do that though)
> and so blindly copying it into the character array of size NAME_MAX
> isn't safe. Instead we must use snprintf() here.

Thanks!

> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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

Re: [PATCH] PM / OPP: Use snprintf() instead of sprintf()

[Stephen Boyd]

On 01/05, Viresh Kumar wrote:
> sprintf() can access memory outside of the range of the character array,
> and is risky in some situations. The driver specified prop_name string
> can be longer than NAME_MAX here (only an attacker will do that though)
> and so blindly copying it into the character array of size NAME_MAX
> isn't safe. Instead we must use snprintf() here.
> 
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---

Acked-by: Stephen Boyd <sboyd@codeaurora.org>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] PM / OPP: Use snprintf() instead of sprintf()

[Rafael J. Wysocki]

On Tuesday, January 05, 2016 04:15:54 PM Viresh Kumar wrote:
> sprintf() can access memory outside of the range of the character array,
> and is risky in some situations. The driver specified prop_name string
> can be longer than NAME_MAX here (only an attacker will do that though)
> and so blindly copying it into the character array of size NAME_MAX
> isn't safe. Instead we must use snprintf() here.
> 
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Applied, thanks!

> ---
>  drivers/base/power/opp/core.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
> index cd230c63aee6..cf351d3dab1c 100644
> --- a/drivers/base/power/opp/core.c
> +++ b/drivers/base/power/opp/core.c
> @@ -808,7 +808,8 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
>  
>  	/* Search for "opp-microvolt-<name>" */
>  	if (dev_opp->prop_name) {
> -		sprintf(name, "opp-microvolt-%s", dev_opp->prop_name);
> +		snprintf(name, sizeof(name), "opp-microvolt-%s",
> +			 dev_opp->prop_name);
>  		prop = of_find_property(opp->np, name, NULL);
>  	}
>  
> @@ -849,7 +850,8 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
>  	/* Search for "opp-microamp-<name>" */
>  	prop = NULL;
>  	if (dev_opp->prop_name) {
> -		sprintf(name, "opp-microamp-%s", dev_opp->prop_name);
> +		snprintf(name, sizeof(name), "opp-microamp-%s",
> +			 dev_opp->prop_name);
>  		prop = of_find_property(opp->np, name, NULL);
>  	}
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.