Bug 512652

Summary:	kernel: use -fno-strict-overflow instead of -fwrapv [rhel-4.9]
Product:	Red Hat Enterprise Linux 4	Reporter:	Eugene Teo (Security Response) <eteo>
Component:	kernel	Assignee:	Red Hat Kernel Manager <kernel-mgr>
Status:	CLOSED WONTFIX	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	high	Docs Contact:
Priority:	high
Version:	4.9	CC:	dhoward, jolsa, jskrabal, lwang, plyons, vgoyal, vmayatsk
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:	512650	Environment:
Last Closed:	2009-07-29 08:10:27 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	512650
Bug Blocks:

Description Eugene Teo (Security Response) 2009-07-20 07:52:54 UTC

+++ This bug was initially created as a clone of Bug #512650 +++

Description of problem:
[PATCH] Don't use '-fwrapv' compiler option: it's buggy in gcc-4.1.x

This causes kernel images that don't run init to completion with certain broken gcc versions.

This fixes kernel bugzilla entry:
	http://bugzilla.kernel.org/show_bug.cgi?id=13012

I suspect the gcc problem is this:
	http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28230

Fix the problem by using the -fno-strict-overflow flag instead, which not only does not exist in the known-to-be-broken versions of gcc (it was introduced later than fwrapv), but seems to be much less disturbing to gcc too: the difference in the generated code by -fno-strict-overflow are smaller (compared to using neither flag) than when using -fwrapv.

Upstream commit:
http://git.kernel.org/linus/a137802ee839ace40079bebde24cfb416f73208a

--- Additional comment from eteo on 2009-07-20 03:49:08 EDT ---

Related to bug 491267.