[PATCH] init, fix initcall blacklist for modules

[Prarit Bhargava <prarit@redhat.com>]

Sorry ... forgot to cc everyone on the last email.

P.

----8<----

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 initcall blacklisting code will now always fail when
comparing module_init() function names.  This patch resolves the issue by
comparing to the length of the function_name.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 init/main.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index 4c17fda5c2ff..09a795e91efe 100644
--- a/init/main.c
+++ b/init/main.c
@@ -708,14 +708,26 @@ static bool __init_or_module initcall_blacklisted(initcall_t fn)
 {
 	struct blacklist_entry *entry;
 	char fn_name[KSYM_SYMBOL_LEN];
+	char *space;
+	int length;
 
 	if (list_empty(&blacklisted_initcalls))
 		return false;
 
 	sprint_symbol_no_offset(fn_name, (unsigned long)fn);
+	/*
+	 * fn will be "function_name [module_name]" where [module_name] is not
+	 * displayed for built-in initcall functions.  Strip off the
+	 * [module_name].
+	 */
+	space = strchrnul(fn_name, ' ');
+	if (!space)
+		length = strlen(fn_name);
+	else
+		length = space - fn_name;
 
 	list_for_each_entry(entry, &blacklisted_initcalls, next) {
-		if (!strcmp(fn_name, entry->buf)) {
+		if (!strncmp(fn_name, entry->buf, length)) {
 			pr_debug("initcall %s blacklisted\n", fn_name);
 			return true;
 		}
-- 
1.7.9.3