Bogus FPE on underflow for exp(double)

[Peter van Hoof]

SRU Justification:

[Impact]
exp() in eglibc causes occasional FP crashes.

[Development Fix]
This is fixed in quantal.

[Stable Fix]
The fix can be backported to quantal.

[Test Case]
Test case is documented in the upstream bug:
http://sourceware.org/bugzilla/show_bug.cgi?id=13705

[Regression Potential]
Changes __kernel_standard_f to __kernel_standard in __exp in eglibc.

--

Glibc version 2.15 has a bug causing spurious FP crashes when calling exp(). It has been reported here:

http://sourceware.org/bugzilla/show_bug.cgi?id=13705

You can find all the details, including a testcase and the patch for libm in this report. I found that the 64-bit version of precise ships a version of glibc that still has this bug. I have not tested the 32-bit version, but I assume it has the same problem.

I am one of the developers of the open source code Cloudy and this bug renders our code completely non-functional. I would therefore like to urge you to ship this patch as an update for the precise distribution, especially since this is a LTS release.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: libc6 2.15-0ubuntu10
ProcVersionSignature: Ubuntu 3.2.0-24.39-generic 3.2.16
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu8
Architecture: amd64
Date: Fri Jun 1 16:33:54 2012
InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
ProcEnviron:
 LC_TIME=en_DK.utf8
 TERM=vt100
 LANG=en_US.UTF-8
 SHELL=/bin/tcsh
SourcePackage: eglibc
UpgradeStatus: Upgraded to precise on 2012-05-07 (25 days ago)

[Peter van Hoof (pvh-7)]

Is anybody looking at this? This is a critical bug that completely breaks our code. Many of our users have Ubuntu installed and are suffering because of this. So a quick fix would be appreciated. The link shown above contains the patch, so fixing this should be easy and quick. An identical bug report against openSUSE was fixed in 28 hours. This report is already more than 3 weeks old...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Robin (rjrwilliams)]

Attached patch from upstream

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "Patch from glibc" of this bug report has been identified as being a patch. The ubuntu-reviewers team has been subscribed to the bug report so that they can review the patch. In the event that this is in fact not a patch you can resolve this situation by removing the tag 'patch' from the bug report and editing the attachment so that it is not flagged as a patch. Additionally, if you are member of the ubuntu-reviewers team please also unsubscribe the team from this bug report.

[This is an automated message performed by a Launchpad user owned by Brian Murray. Please contact him regarding any issues with the action taken in this bug report.]

[Launchpad Janitor (janitor)]

This bug was fixed in the package eglibc - 2.15-0ubuntu17

---------------
eglibc (2.15-0ubuntu17) quantal; urgency=low

  * Backport fix from 2.16 for sscanf/realloc deadlock (LP: #1028038)
  * Backport for bogus FPE on underflow for exp(double) (LP: #1007457)
 -- Adam Conrad <email address hidden> Thu, 09 Aug 2012 20:25:35 -0600

[Clint Byrum (clint-fewbar)]

Hello Peter, or anyone else affected,

Accepted eglibc into precise-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/eglibc/2.15-0ubuntu10.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please change the bug tag from verification-needed to verification-done. If it does not, change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Robin (rjrwilliams)]

Fix is **not** released for Precise.

My apologies, I clicked on a link and didn't realize it would make any change (let alone an irrevocable one). Trac is more forgiving...

[Adam Conrad (adconrad)]

Marking back to Fix Committed until it's actually released to -updates.

[Brian Murray (brian-murray)]

Hello Peter, or anyone else affected,

Accepted eglibc into precise-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/eglibc/2.15-0ubuntu10.3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please change the bug tag from verification-needed to verification-done. If it does not, change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Adam Conrad (adconrad)]

Peter, can you re-test with 2.15-0ubuntu10.3 and verify that it still fixes the problem for you? It was superseded by a security update, and I had to re-upload all over again.

[Peter van Hoof (pvh-7)]

The math library in libc6-amd64_2.15-0ubuntu10.3_i386.deb fixes the bug.

[Colin Watson (cjwatson)]

The verification of this Stable Release Update has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regresssions.

[Adam Conrad (adconrad)]

This bug was fixed in the package eglibc - 2.15-0ubuntu10.3

---------------
eglibc (2.15-0ubuntu10.3) precise; urgency=low

  * Backport fixes for dbl-64 and ldbl-128 issues (LP: #1000498)
  * Backport another FMA support patch from glibc master branch.

eglibc (2.15-0ubuntu10.2) precise-security; urgency=low

  * SECURITY UPDATE: stack buffer overflow in vfprintf handling
    (LP: #1031301)
    - debian/patches/any/CVE-2012-3406.patch: switch to malloc when
      array grows too large to handle via alloca extension
    - CVE-2012-3406
  * SECURITY UPDATE: stdlib strtod integer/buffer overflows
    - debian/patches/any/CVE-2012-3480.patch: rearrange calculations
      and modify types to void integer overflows
    - CVE-2012-3480

eglibc (2.15-0ubuntu10.1) precise; urgency=low

  * Backport fix from 2.16 to fix htons() conversion errors on non-x86
    architectures, by correctly casting to uint16_t (LP: #1016349)
  * Restore missing AT_EMPTY_PATH definition in fnctl.h (LP: #1010069)
  * Backport FMA4/AVX detection from glibc 2.16 (LP: #956051, #979003)
  * Backport fixups to AVX-using code to match the detection backport.
  * Backport fix from 2.16 for sscanf/realloc deadlock (LP: #1028038)
  * Backport for bogus FPE on underflow for exp(double) (LP: #1007457)
 -- Adam Conrad <email address hidden> Wed, 03 Oct 2012 15:58:02 -0600