powerpc/fadump: use kstrtoint to handle sysfs store

Currently sysfs store handlers in fadump use if buf[0] == 'char'.

This means input "100foo" is interpreted as '1' and "01" as '0'.

Change to kstrtoint so leading zeroes and the like is handled in
expected way.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michal Suchanek <a class="moz-txt-link-rfc2396E" href="mailto:msuchanek@suse.de">&lt;msuchanek@suse.de&gt;</a></pre>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/fadump.c

@@ -1270,10 +1270,15 @@ static ssize_t fadump_release_memory_store(struct kobject *kobj,
 					struct kobj_attribute *attr,
 					const char *buf, size_t count)
 {
+	int input = -1;
+
 	if (!fw_dump.dump_active)
 		return -EPERM;
 
-	if (buf[0] == '1') {
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
+	if (input == 1) {
 		/*
 		 * Take away the '/proc/vmcore'. We are releasing the dump
 		 * memory, hence it will not be valid anymore.
@@ -1307,21 +1312,25 @@ static ssize_t fadump_register_store(struct kobject *kobj,
 					const char *buf, size_t count)
 {
 	int ret = 0;
+	int input = -1;
 
 	if (!fw_dump.fadump_enabled || fdm_active)
 		return -EPERM;
 
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
 	mutex_lock(&fadump_mutex);
 
-	switch (buf[0]) {
-	case '0':
+	switch (input) {
+	case 0:
 		if (fw_dump.dump_registered == 0) {
 			goto unlock_out;
 		}
 		/* Un-register Firmware-assisted dump */
 		fadump_unregister_dump(&fdm);
 		break;
-	case '1':
+	case 1:
 		if (fw_dump.dump_registered == 1) {
 			ret = -EEXIST;
 			goto unlock_out;