Bug 491266 - kernel should be built with -fwrapv [rhel-5.4]
kernel should be built with -fwrapv [rhel-5.4]
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel (Show other bugs)
All Linux
urgent Severity high
: rc
: ---
Assigned To: Don Zickus
Red Hat Kernel QE team
: ZStream
Depends On:
Blocks: 501751
  Show dependency treegraph
Reported: 2009-03-20 02:33 EDT by Eugene Teo (Security Response)
Modified: 2009-09-02 04:06 EDT (History)
10 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2009-09-02 04:06:01 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
Upstream patch (1.25 KB, patch)
2009-03-20 02:34 EDT, Eugene Teo (Security Response)
no flags Details | Diff

  None (edit)
Description Eugene Teo (Security Response) 2009-03-20 02:33:07 EDT
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 Product and Program Management 2009-05-18 23:49:27 EDT
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 11:36:35 EDT
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 04:02:25 EDT
See bug 512650. Use -fno-strict-overflow instead of -fwrapv.
Comment 14 errata-xmlrpc 2009-09-02 04:06:01 EDT
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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