Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938394AbcJZM0g (ORCPT ); Wed, 26 Oct 2016 08:26:36 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55166 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965831AbcJZM00 (ORCPT ); Wed, 26 Oct 2016 08:26:26 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miklos Szeredi Subject: [PATCH 4.8 063/140] ovl: copy_up_xattr(): use strnlen Date: Wed, 26 Oct 2016 14:22:03 +0200 Message-Id: <20161026122223.089368639@linuxfoundation.org> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20161026122220.384323763@linuxfoundation.org> References: <20161026122220.384323763@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1385 Lines: 48 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miklos Szeredi 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. Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/copy_up.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -57,6 +57,7 @@ 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) @@ -79,7 +80,16 @@ 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: