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Bug 512650

Summary: kernel: use -fno-strict-overflow instead of -fwrapv [rhel-5.4]
Product: Red Hat Enterprise Linux 5 Reporter: Eugene Teo (Security Response) <eteo>
Component: kernelAssignee: Danny Feng <dfeng>
Status: CLOSED WONTFIX QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: high Docs Contact:
Priority: high    
Version: 5.4CC: dhoward, dzickus, jpirko, jskrabal, lwang, plyons, syeghiay
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 512652 512653 (view as bug list) Environment:
Last Closed: 2009-07-29 07:59:55 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:    
Bug Blocks: 512652, 512653    
Attachments:
Description Flags
posted patch none

Description Eugene Teo (Security Response) 2009-07-20 07:44:42 UTC 
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
Comment 1 Eugene Teo (Security Response) 2009-07-20 07:49:08 UTC 
Related to bug 491266.
Comment 5 Danny Feng 2009-07-29 01:36:09 UTC 
Created attachment 355478 [details]
posted patch