strict_strto* is not strict enough

It decodes "\n" as 0, which is bad, because stray echo into backlight
will turn your backlight off, etc...

Signed-off-by: Pavel Machek <pavel@suse.cz>
Cc: Yi Yang <yi.y.yang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/vsprintf.c

@@ -170,6 +170,8 @@ int strict_strtoul(const char *cp, unsigned int base, unsigned long *res)
 		return -EINVAL;
 
 	val = simple_strtoul(cp, &tail, base);
+	if (tail == cp)
+		return -EINVAL;
 	if ((*tail == '\0') ||
 		((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {
 		*res = val;
@@ -241,6 +243,8 @@ int strict_strtoull(const char *cp, unsigned int base, unsigned long long *res)
 		return -EINVAL;
 
 	val = simple_strtoull(cp, &tail, base);
+	if (tail == cp)
+		return -EINVAL;
 	if ((*tail == '\0') ||
 		((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {
 		*res = val;