Patch "ovl: copy_up_xattr(): use strnlen" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

ovl: copy_up_xattr(): use strnlen

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ovl-copy_up_xattr-use-strnlen.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Miklos Szeredi <[email protected]>
Date: Fri, 16 Sep 2016 14:12:11 +0200
Subject: ovl: copy_up_xattr(): use strnlen

From: Miklos Szeredi <[email protected]>

commit 8b326c61de08f5ca4bc454a168f19e7e43c4cc2a upstream.

Be defensive about what underlying fs provides us in the returned xattr list buffer. strlen() may overrun the buffer, so use strnlen() and WARN if the contents are not properly null terminated.

---
 fs/overlayfs/copy_up.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

@@ -25,6 +25,7 @@ int ovl_copy_xattr(struct dentry *old, s
 	ssize_t list_size, size, value_size = 0;
 	char *buf, *name, *value = NULL;
 	int uninitialized_var(error);
+	size_t slen;
 
 	if (!old->d_inode->i_op->getxattr ||
 	    !new->d_inode->i_op->getxattr)

@@ -47,7 +48,16 @@ int ovl_copy_xattr(struct dentry *old, s
 		goto out;
 	}
 
-	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
+	for (name = buf; list_size; name += slen) {
+		slen = strnlen(name, list_size) + 1;
+
+		/* underlying fs providing us with an broken xattr list? */
+		if (WARN_ON(slen > list_size)) {
+			error = -EIO;
+			break;
+		}
+		list_size -= slen;
+
 		if (ovl_is_private_xattr(name))
 			continue;
 retry:

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/ovl-fix-info-leak-in-ovl_lookup_temp.patch queue-4.4/ovl-copy_up_xattr-use-strnlen.patch