linux-kernel - [PATCH] adjust suspicious memset in nfsacl

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Date:	Wed, 02 Feb 2011 00:14:45 -0600
From:	Milton Miller <miltonm@....com>
To:	Chuck Lever <chuck.lever@...cle.com>,
	Trond Myklebust <Trond.Myklebust@...app.com>
Cc:	"J. Bruce Fields" <bfields@...ldses.org>,
	Neil Brown <neilb@...e.de>, <linux-nfs@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] adjust suspicious memset in nfsacl_encode()


commit f61f6da0d53842e849bab7f69e1431bd3de1136d "NFS: Prevent memory
allocation failure in nfsacl_encode()" added a memset whose length was
the size of the pointer.  Change this to the size of the pointed struct
that is later passed to posix_acl_init().  The 4 entries that are the
remainder of the parent struct will be set and therefore should not
need zeroing.

Alternatively we could remove the memset as posix_acl_init sets all
fields with storage in struct posix_acl and we won't reference any
implicit padding.

Signed-off-by: Milton Miller <miltonm@....com>
---
While I was reviewing changes merged post rc2 I saw this suspicious memset.

diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c
index 84c27d6..bc6d81b 100644
--- a/fs/nfs_common/nfsacl.c
+++ b/fs/nfs_common/nfsacl.c
@@ -117,7 +117,7 @@ int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
 		 * invoked in contexts where a memory allocation failure is
 		 * fatal.  Fortunately this fake ACL is small enough to
 		 * construct on the stack. */
-		memset(acl2, 0, sizeof(acl2));
+		memset(acl2, 0, sizeof(*acl2));
 		posix_acl_init(acl2, 4);
 
 		/* Insert entries in canonical order: other orders seem
--
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