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

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

[Liuweni]

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

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

[Matthew Wilcox]

On Thu, Dec 17, 2009 at 10:15:43PM +0800, Liuweni wrote:
> 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. 

All the callers of posix_acl_valid() currently check for acl being a
null pointer themselves.  Moving the check to posix_acl_valid() certainly
seems like a good idea to me, but you need to delete the check from all
the callers.

Further, it seems like many of the callers might have a PTR_ERR value
for 'acl', so you should also move this check into posix_acl_valid().

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."