[PATCH 1/3]posix acl:Add an acl check

["Liuweni" <qingshenlwy@gmail.com>]

In this function, the parameter of acl will be called by FOREACH_ACL_ENTRY(macro) 
without null point check. I add a null point check to it. 

---
Signed-off-by: Liuwenyi <qingshenlwy@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 39df95a..956df14 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -76,6 +76,9 @@ posix_acl_valid(const struct posix_acl *acl)
 	unsigned int id = 0;  /* keep gcc happy */
 	int needs_mask = 0;
 
+	if (!acl)
+		return -EINVAL;
+
 	FOREACH_ACL_ENTRY(pa, acl, pe) {
 		if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
 			return -EINVAL;

 				
--------------
Best Regards,
Liuweni
2009-12-17