[arm64] libmozjs24 crashes w/ 48-bit VA

[dann frazier]

[Impact]
libmozjs24 does not support 48-bit virtual addresses on arm64. 48-bit virtual addresses are enabled in the Ubuntu 16.04 kernel (though not on the kernel used on the buildds). This causes applications to crash.

[Test Case]
= mozjs =
$ sudo apt install couchdb-bin
$ couchjs a.js
Segmentation fault

= mozjs24 =
$ cat a.js
print("hello")
$ js24 a.js
Segmentation fault

[Regression Risk]
The fix for mozjs24 is ifdef'd to only apply to arm64. Since arm64 is currently segfaulting with a very simple program, there's very little chance of making things worse.

[Jeremy Bícha (jbicha)]

Dann, do you want to try the new mozjs24 24.2.0-5.1ubuntu1 in zesty? I don't have arm64 hardware.

[dann frazier (dannf)]

On Sun, Jan 8, 2017 at 4:36 PM, Jeremy Bicha <email address hidden> wrote:
> Dann, do you want to try the new mozjs24 24.2.0-5.1ubuntu1 in zesty? I
> don't have arm64 hardware.

Jeremy,
 I can confirm that the package builds fine. If I revert
manually-mmap-on-arm64-to-ensure-high-17-bits-are-clear.patch, the
problem resurfaces. Thanks!

  -dann

[Brian Murray (brian-murray)]

Hello dann, or anyone else affected,

Accepted mozjs24 into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/mozjs24/24.2.0-3ubuntu2.1 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 on 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 add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

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

[dann frazier (dannf)]

ubuntu@alekhin:~$ cat > a.js
print("hello")
ubuntu@alekhin:~$ js24 a.js
Segmentation fault (core dumped)
ubuntu@alekhin:~$ sudo dpkg -i libmozjs-24-bin_24.2.0-3ubuntu2.1_arm64.deb
(Reading database ... 101897 files and directories currently installed.)
Preparing to unpack libmozjs-24-bin_24.2.0-3ubuntu2.1_arm64.deb ...
Unpacking libmozjs-24-bin (24.2.0-3ubuntu2.1) over (24.2.0-3ubuntu2) ...
Setting up libmozjs-24-bin (24.2.0-3ubuntu2.1) ...
ubuntu@alekhin:~$ js24 a.js
hello
ubuntu@alekhin:~$

[Launchpad Janitor (janitor)]

This bug was fixed in the package mozjs24 - 24.2.0-3ubuntu2.1

---------------
mozjs24 (24.2.0-3ubuntu2.1) xenial; urgency=medium

  * Manually mmap on arm64 to ensure high 17 bits are clear (LP: #1571017)
    Thanks to Zheng Xu.

 -- dann frazier <email address hidden> Thu, 26 Apr 2018 13:53:45 -0600

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for mozjs24 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 regressions.