From: Lachlan McIlroy Subject: [PATCH] e2fsck: fix floating point precision error Date: Wed, 30 Jun 2010 00:54:40 -0400 (EDT) Message-ID: <550740039.484761277873680181.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> References: <352298559.484441277873349806.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> Reply-To: Lachlan McIlroy Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: ext4 development Return-path: Received: from mx3-phx2.redhat.com ([209.132.183.24]:37999 "EHLO mx01.colomx.prod.int.phx2.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751300Ab0F3Eyk (ORCPT ); Wed, 30 Jun 2010 00:54:40 -0400 Received: from mail05.corp.redhat.com (zmail05.collab.prod.int.phx2.redhat.com [10.5.5.46]) by mx01.colomx.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o5U4se1m017730 for ; Wed, 30 Jun 2010 00:54:40 -0400 In-Reply-To: <352298559.484441277873349806.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Fix floating point precision error in e2fsck. Commit 641b66bc7ee0a880b0eb0125dff5f8ed8dd5a160 fixed a floating point precision error which can result in a search algorithm looping forever. It can also result in an array index being out of bounds and causing a segfault. Here are two more cases that need to be fixed. I've just used the same fix from the that commit. diff -up e2fsprogs-1.39/e2fsck/ea_refcount.c.orig e2fsprogs-1.39/e2fsck/ea_refcount.c --- e2fsprogs-1.39/e2fsck/ea_refcount.c.orig 2010-06-30 11:14:51.516239079 +1000 +++ e2fsprogs-1.39/e2fsck/ea_refcount.c 2010-06-30 11:22:22.277362222 +1000 @@ -193,9 +193,14 @@ retry: range = 0; else if (blk > highval) range = 1; - else + else { range = ((float) (blk - lowval)) / (highval - lowval); + if (range > 0.9) + range = 0.9; + if (range < 0.1) + range = 0.1; + } mid = low + ((int) (range * (high-low))); } #endif diff -up e2fsprogs-1.39/resize/extent.c.orig e2fsprogs-1.39/resize/extent.c --- e2fsprogs-1.39/resize/extent.c.orig 2010-06-30 11:25:58.969188333 +1000 +++ e2fsprogs-1.39/resize/extent.c 2010-06-30 11:26:40.449327216 +1000 @@ -167,9 +167,14 @@ __u32 ext2fs_extent_translate(ext2_exten range = 0; else if (old_loc > highval) range = 1; - else + else { range = ((float) (old_loc - lowval)) / (highval - lowval); + if (range > 0.9) + range = 0.9; + if (range < 0.1) + range = 0.1; + } mid = low + ((int) (range * (high-low))); } #endif Lachlan