kallsyms: Use bounded strnchr() when parsing string

When parsing for the <module:name> format, we use strchr() to look for
the separator, when we know that the module name can't be longer than
MODULE_NAME_LEN. Enforce the same using strnchr().
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NJessica Yu <jeyu@redhat.com>

kernel/module.c

@@ -4017,7 +4017,7 @@ unsigned long module_kallsyms_lookup_name(const char *name)
 
 	/* Don't lock: we're in enough trouble already. */
 	preempt_disable();
-	if ((colon = strchr(name, ':')) != NULL) {
+	if ((colon = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {
 		if ((mod = find_module_all(name, colon - name, false)) != NULL)
 			ret = mod_find_symname(mod, colon+1);
 	} else {