Red Hat Bugzilla – Bug 491266
kernel should be built with -fwrapv [rhel-5.4]
Last modified: 2009-09-02 04:06:01 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
Not all versions of gcc support it, so we need to make it conditional (it looks
like it was introduced in gcc-3.4).
Created attachment 335960 [details]
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
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.
See bug 512650. Use -fno-strict-overflow instead of -fwrapv.
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.