[34-longterm 186/260] ocfs2: Don't walk off the end of fast symlinks.

From: Paul Gortmaker
Date: Sun Jan 02 2011 - 02:42:33 EST

From: Joel Becker <joel.becker@xxxxxxxxxx>

commit 1fc8a117865b54590acd773a55fbac9221b018f0 upstream.

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@xxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
fs/ocfs2/symlink.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

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;

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