PM / OPP: Use snprintf() instead of sprintf()

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: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

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);
 	}