linux-kernel - [PATCH] simple_xattr: permit 0-size extended attributes

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Message-ID: <alpine.LSU.2.11.1407161313210.7782@eggly.anvils>
Date:	Wed, 16 Jul 2014 13:14:06 -0700 (PDT)
From:	Hugh Dickins <hughd@...gle.com>
To:	Al Viro <viro@...iv.linux.org.uk>
cc:	Jeff Layton <jlayton@...chiereds.net>,
	Aristeu Rozanski <aris@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] simple_xattr: permit 0-size extended attributes

If a filesystem uses simple_xattr to support user extended attributes,
LTP setxattr01 and xfstests generic/062 fail with "Cannot allocate memory":
simple_xattr_alloc()'s wrap-around test mistakenly excludes values of zero
size.  Fix that off-by-one (but apparently no filesystem needs them yet).

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---

 fs/xattr.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 3.16-rc5/fs/xattr.c	2013-02-18 15:58:34.000000000 -0800
+++ linux/fs/xattr.c	2014-07-16 12:47:10.640004412 -0700
@@ -843,7 +843,7 @@ struct simple_xattr *simple_xattr_alloc(
 
 	/* wrap around? */
 	len = sizeof(*new_xattr) + size;
-	if (len <= sizeof(*new_xattr))
+	if (len < sizeof(*new_xattr))
 		return NULL;
 
 	new_xattr = kmalloc(len, GFP_KERNEL);
--
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