linux-kernel - [PATCH] init, fix initcall blacklist for modules

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Message-Id: <1465820830-13421-1-git-send-email-prarit@redhat.com>
Date:	Mon, 13 Jun 2016 08:27:10 -0400
From:	Prarit Bhargava <prarit@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Prarit Bhargava <prarit@...hat.com>
Subject: [PATCH] init, fix initcall blacklist for modules

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@...hat.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