Bug 491266 - kernel should be built with -fwrapv [rhel-5.4]
Summary: kernel should be built with -fwrapv [rhel-5.4]
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.4
Hardware: All
OS: Linux
Target Milestone: rc
: ---
Assignee: Don Zickus
QA Contact: Red Hat Kernel QE team
Depends On:
Blocks: 501751
TreeView+ depends on / blocked
Reported: 2009-03-20 06:33 UTC by Eugene Teo (Security Response)
Modified: 2009-09-02 08:06 UTC (History)
10 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2009-09-02 08:06:01 UTC
Target Upstream Version:

Attachments (Terms of Use)
Upstream patch (1.25 KB, patch)
2009-03-20 06:34 UTC, Eugene Teo (Security Response)
no flags Details | Diff

System ID Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2009:1243 normal SHIPPED_LIVE Important: Red Hat Enterprise Linux 5.4 kernel security and bug fix update 2009-09-01 08:53:34 UTC

Description Eugene Teo (Security Response) 2009-03-20 06:33:07 UTC
Description of problem:
Add '-fwrapv' to gcc CFLAGS. This makes sure that gcc doesn't try to optimize
away wrapping arithmetic, which the kernel occasionally uses for overflow
testing, ie things like

if (ptr + offset < ptr)

which technically is undefined for non-unsigned types. See


for details.

Not all versions of gcc support it, so we need to make it conditional (it looks
like it was introduced in gcc-3.4).

Comment 7 RHEL Program Management 2009-05-19 03:49:27 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update

Comment 9 Don Zickus 2009-05-21 15:36:35 UTC
in kernel-2.6.18-150.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Please do NOT transition this bugzilla state to VERIFIED until our QE team
has sent specific instructions indicating when to do so.  However feel free
to provide a comment indicating that this fix has been verified.

Comment 12 Eugene Teo (Security Response) 2009-07-20 08:02:25 UTC
See bug 512650. Use -fno-strict-overflow instead of -fwrapv.

Comment 14 errata-xmlrpc 2009-09-02 08:06:01 UTC
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.


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