[PATCH 2/3]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 pointer check. 

I add a Null point checker to it. 

In the fs/btrfs/btrfs_acl.c, the posix_acl_equiv_mode will make a error by null pointer.


---
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..37d0485 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -150,6 +150,9 @@ posix_acl_equiv_mode(const struct posix_acl *acl, mode_t *mode_p)
 	mode_t mode = 0;
 	int not_equiv = 0;
 
+	if(!acl)
+		return -EINVAL;
+
 	FOREACH_ACL_ENTRY(pa, acl, pe) {
 		switch (pa->e_tag) {
 			case ACL_USER_OBJ:

 				
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Best Regards,
Liuweni
2009-12-17