firmware: arm_scpi: Fix string overflow in SCPI genpd driver

Without the bound checks for scpi_pd->name, it could result in the buffer
overflow when copying the SCPI device name from the corresponding device
tree node as the name string is set at maximum size of 30.

Let us fix it by using devm_kasprintf so that the string buffer is
allocated dynamically.

Fixes: 8bec4337 ("firmware: scpi: add device power domain support using genpd")
Reported-by: Pedro Batista <pedbap.g@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: stable@vger.kernel.org
Cc: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20211209120456.696879-1-sudeep.holla@arm.com'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/firmware/scpi_pm_domain.c

@@ -16,7 +16,6 @@ struct scpi_pm_domain {
 	struct generic_pm_domain genpd;
 	struct scpi_ops *ops;
 	u32 domain;
-	char name[30];
 };
 
 /*
@@ -110,8 +109,13 @@ static int scpi_pm_domain_probe(struct platform_device *pdev)
 
 		scpi_pd->domain = i;
 		scpi_pd->ops = scpi_ops;
-		sprintf(scpi_pd->name, "%pOFn.%d", np, i);
-		scpi_pd->genpd.name = scpi_pd->name;
+		scpi_pd->genpd.name = devm_kasprintf(dev, GFP_KERNEL,
+						     "%pOFn.%d", np, i);
+		if (!scpi_pd->genpd.name) {
+			dev_err(dev, "Failed to allocate genpd name:%pOFn.%d\n",
+				np, i);
+			continue;
+		}
 		scpi_pd->genpd.power_off = scpi_pd_power_off;
 		scpi_pd->genpd.power_on = scpi_pd_power_on;