From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753077AbcFFOjq (ORCPT ); Mon, 6 Jun 2016 10:39:46 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58851 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752329AbcFFOaE (ORCPT ); Mon, 6 Jun 2016 10:30:04 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Luis de Bethencourt , David Sterba Subject: [PATCH 4.5 112/128] btrfs: avoid overflowing f_bfree Date: Sun, 5 Jun 2016 15:24:27 -0700 Message-Id: <20160605222324.785526265@linuxfoundation.org> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160605222321.183131188@linuxfoundation.org> References: <20160605222321.183131188@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 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luis de Bethencourt commit 41b34accb265e3a20211a7a8ef3625678f1c6ec7 upstream. Since mixed block groups accounting isn't byte-accurate and f_bree is an unsigned integer, it could overflow. Avoid this. Signed-off-by: Luis de Bethencourt Suggested-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/super.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2073,7 +2073,11 @@ static int btrfs_statfs(struct dentry *d /* Account global block reserve as used, it's in logical size already */ spin_lock(&block_rsv->lock); - buf->f_bfree -= block_rsv->size >> bits; + /* Mixed block groups accounting is not byte-accurate, avoid overflow */ + if (buf->f_bfree >= block_rsv->size >> bits) + buf->f_bfree -= block_rsv->size >> bits; + else + buf->f_bfree = 0; spin_unlock(&block_rsv->lock); buf->f_bavail = div_u64(total_free_data, factor);