From: Joel Becker <joel.becker@oracle.com>
Date: Thu, 30 Sep 2010 00:33:05 +0000 (-0700)
Subject: ocfs2: Don't walk off the end of fast symlinks.
X-Git-Tag: v3.0~3233^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1fc8a117865b54590acd773a55fbac9221b018f0;p=platform%2Fkernel%2Flinux-amlogic.git

ocfs2: Don't walk off the end of fast symlinks.

ocfs2 fast symlinks are NUL terminated strings stored inline in the
inode data area.  However, disk corruption or a local attacker could, in
theory, remove that NUL.  Because we're using strlen() (my fault,
introduced in a731d1 when removing vfs_follow_link()), we could walk off
the end of that string.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Cc: stable@kernel.org
---

diff --git a/fs/ocfs2/symlink.c b/fs/ocfs2/symlink.c
index 32499d21..9975457 100644
--- a/fs/ocfs2/symlink.c
+++ b/fs/ocfs2/symlink.c
@@ -128,7 +128,7 @@ static void *ocfs2_fast_follow_link(struct dentry *dentry,
 	}
 
 	/* Fast symlinks can't be large */
-	len = strlen(target);
+	len = strnlen(target, ocfs2_fast_symlink_chars(inode->i_sb));
 	link = kzalloc(len + 1, GFP_NOFS);
 	if (!link) {
 		status = -ENOMEM;