init: allow blacklisting of module_init functions

sprint_symbol_no_offset() returns the string "function_name
[module_name]" where [module_name] is not printed for built in kernel
functions.  This means that the blacklisting code will fail when
comparing module function names with the extended string.

This patch adds the functionality to block a module's module_init()
function by finding the space in the string and truncating the
comparison to that length.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Prarit Bhargava <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Yaowei Bai <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Rusty Russell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

init/main.c

@@ -716,6 +716,12 @@ static bool __init_or_module initcall_blacklisted(initcall_t fn)
 	addr = (unsigned long) dereference_function_descriptor(fn);
 	sprint_symbol_no_offset(fn_name, addr);
 
+	/*
+	 * fn will be "function_name [module_name]" where [module_name] is not
+	 * displayed for built-in init functions.  Strip off the [module_name].
+	 */
+	strreplace(fn_name, ' ', '\0');
+
 	list_for_each_entry(entry, &blacklisted_initcalls, next) {
 		if (!strcmp(fn_name, entry->buf)) {
 			pr_debug("initcall %s blacklisted\n", fn_name);