[SRU] pthread_rwlock_trywrlock results in hang

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JFTR RHEL 8 and FC30 has already pulled the fix into their glibc, so it's really only Ubuntu and Debian affected by this.

According to upstream, the issue first appeared in 2.26, so only bionic is affected.

JFTR Debian 2.28-8 has already the fix applied.

Test case. Build with:

gcc bug23844.wr.c -lpthread -o bug23844wr

I created a ppa with the fix for bionic: https://launchpad.net/~ahasenack/+archive/ubuntu/glibc-pthread-lock-23844/

After updating to that package, the test case program no longer hangs (counted 75 runs, whereas before it would hang in at most 5).

Git branch: https://code.launchpad.net/~ahasenack/ubuntu/+source/glibc/+git/glibc/+ref/bionic-glibc-thread-lock-23844

@nish pointed out in the MP that I had the incorrect packaging version for an SRU. Since the correct version is lower than what I uploaded before, I created a new ppa:

https://launchpad.net/~ahasenack/+archive/ubuntu/glibc-pthread-lock-1864864

Packages are still building there, but other than the version, they are the same.

Can someone who is affected by this bug, and able to reproduce it in a test/controlled environment, please try the glibc packages from my PPA? Note you will have to restart services after the update (or better yet, reboot if you can):

https://launchpad.net/~ahasenack/+archive/ubuntu/glibc-pthread-lock-1864864

Yes your ppa and an affected bind package build no longer hang.

I'm preparing the SRU in https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/4242/+packages with the fix in.

Hello Ondřej, or anyone else affected,

Accepted glibc into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/glibc/2.27-3ubuntu1.3 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 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, what testing has been performed on the package and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. 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 for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Bionic verification

First, reproducing the bug with the current glibc:
ubuntu@bionic-glibc-1864864:~$ apt-cache policy libc6
libc6:
  Installed: 2.27-3ubuntu1.2
  Candidate: 2.27-3ubuntu1.2
  Version table:
 *** 2.27-3ubuntu1.2 500
        500 http://br.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://br.archive.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        100 /var/lib/dpkg/status

It hung immediately:
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
(stuck)

Second run worked, third run got stuck again:
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
(stuck)

With updated glibc:
ubuntu@bionic-glibc-1864864:~$ apt-cache policy libc6
libc6:
  Installed: 2.27-3ubuntu1.3
  Candidate: 2.27-3ubuntu1.3
  Version table:
 *** 2.27-3ubuntu1.3 500
        500 http://br.archive.ubuntu.com/ubuntu bionic-proposed/main amd64 Packages
        100 /var/lib/dpkg/status

Sample program doesn't hang anymore, after multiple tries, and no need to rebuild it:
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000
ubuntu@bionic-glibc-1864864:~$ ./bug23844wr
trylock_wr
500000

bionic verification succeeded

All autopkgtests for the newly accepted glibc (2.27-3ubuntu1.3) for bionic have finished running.
The following regressions have been reported in tests triggered by the package:

mysql-5.7/5.7.31-0ubuntu0.18.04.1 (armhf)
libsys-utmp-perl/1.8-1 (armhf)
libscope-upper-perl/0.30-1 (armhf)
octave-miscellaneous/1.2.1-4 (armhf, arm64, s390x, amd64, i386, ppc64el)
libsocket-multicast6-perl/unknown (armhf)
octave-strings/1.2.0-3 (armhf, arm64, s390x, amd64, i386, ppc64el)
libgnatcoll/unknown (armhf)
octave-econometrics/1:1.1.1-5 (armhf, arm64, s390x, amd64, i386, ppc64el)
octave-secs2d/0.0.8-9 (armhf, arm64, s390x, amd64, i386, ppc64el)
libb-hooks-parser-perl/unknown (armhf)
octave-general/2.0.0-3 (armhf, arm64, s390x, amd64, i386, ppc64el)
libcompress-raw-bzip2-perl/2.074-1build2 (armhf)
libunicode-casefold-perl/unknown (armhf)
mod-wsgi/4.5.17-1ubuntu1 (ppc64el)
libdata-alias-perl/unknown (armhf)
libdata-clone-perl/unknown (armhf)
libsort-key-perl/unknown (armhf)
linux-raspi-5.4/5.4.0-1018.20~18.04.1 (armhf)
ann/unknown (armhf)
icecast2/unknown (i386)
python-maxminddb/1.3.0-1 (armhf)
lua-torch-sundown/unknown (armhf)
libkf5mailcommon/4:17.12.3-0ubuntu1 (arm64, i386)
apport/2.20.9-0ubuntu7.17 (amd64)
linux-hwe-5.0/5.0.0-61.65 (armhf)
ffmpeg/7:3.4.8-0ubuntu0.2 (armhf, arm64, s390x, amd64, i386, ppc64el)
glibc/2.27-3ubuntu1.3 (armhf)
nut/2.7.4-5.1ubuntu2 (amd64)
mbuffer/unknown (armhf)
linux-aws-edge/5.0.0-1019.21~18.04.1 (amd64, arm64)
octave-ocs/0.1.5-6 (armhf, arm64, s390x, amd64, i386, ppc64el)
libx11-xcb-perl/unknown (armhf)
pgbouncer/1.8.1-1build1 (amd64)
indicator-session/17.3.20+17.10.20171006-0ubuntu1 (armhf)
gcc-6/6.5.0-2ubuntu1~18.04 (armhf)
vmtouch/unknown (armhf)
libhtml-gumbo-perl/0.17-1build1 (ppc64el)
octave-sparsersb/1.0.5-3 (armhf, arm64, s390x, amd64, i386, ppc64el)
octave-mpi/1.2.0-4 (armhf, arm64, s390x, amd64, i386, ppc64el)
libalgorithm-svm-perl/0.13-2build2 (s390x)
libconvert-binary-c-perl/0.78-1build2 (amd64)
kauth/5.44.0-0ubuntu1 (i386)
libkdegames-kde4/unknown (amd64)
openssh/1:7.6p1-4ubuntu0.3 (armhf, arm64, s390x, amd64, i386, ppc64el)
keditbookmarks/17.12.3-0ubuntu1 (ppc64el)
jovie/unknown (armhf)
kdepim-runtime/4:17.12.3-0ubuntu2 (armhf)
libscalar-util-numeric-perl/0.40-1build3 (s390x)
pgpdump/unknown (armhf)
libdevice-cdio-perl/0.4.0-3 (armhf)
octave-sockets/1.2.0-3 (armhf, arm64, s390x, amd64, i386, ppc64el)
octave-gsl/2.1.0-3 (armhf, arm64, s390x, amd64, i386, ppc64el)
libdbd-odbc-perl/1.56-1build1 (armhf)
libnet-dbus-perl/1.1.0-4build2 (armhf)
linux-aws-5.3/unknown (arm64)
libalgorithm-permute-perl/0.16-1 (s390x)
xdg-desktop-portal/1.0.3-0ubuntu0.2 (i386, ppc64el)
octave-ltfat/2.2.0+dfsg-7 (s390x, amd64, i386, ppc64el)
octave-geometry/3.0.0-6 (armhf, arm64, s390x, amd64, i386, ppc64el)
octave-linear-algebra/2.2.2-4 (armhf, arm64, s390x, amd64, i386, ppc64el)
octave-nurbs/1.3.13-4 (armhf, arm64, s390x, amd64, i386, ppc64el)
devscripts/2.17.12ubuntu1.1 (armhf, arm64, s390x, amd64, i386, ppc64el)
meliae/0.4.0+bzr199-3build1 (ppc64el)
libocas/unknown (armhf)
k3d/unknown (armhf)
firefox/80.0.1+build1-0ubuntu0.18.04.1 (armhf)
libb-hooks-op-check-perl/unknown (armhf)
octave-quaternion/2.4.0-4 (armhf, arm64, s390x, amd64, i38...

The verification of the Stable Release Update for glibc has completed successfully and the package is now being 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.

This bug was fixed in the package glibc - 2.27-3ubuntu1.3

---------------
glibc (2.27-3ubuntu1.3) bionic; urgency=medium

  [ Balint Reczey ]
  * debian/gbp.conf: Add initial configuration
  * debian/control.in/main: Add Vcs-* pointing to Ubuntu packaging repository
  * arm64: Enable searching shared libraries in atomics/ on LSE HW
  * Ship arm64 variant with LSE support in libc6-lse (LP: #1885012)
  * Run tests of libc6-lse on HW supporting LSE
  * debian/patches/git-updates.diff: update from upstream stable branch
    - pthread_cond_broadcast: Fix waiters-after-spinning case
    - Fix SSe2-based memmove corrupting memory (CVE-2017-18269)
    - Fix strstr() performance regression on Haswell processors
    - Support Japanese new era "令和 (Reiwa)"
    - io: Remove copy_file_range emulation
    (LP: #1851263, #1858203, #1838327, #1797335, #1756209, #1853193)
  * XFAIL stdlib/tst-getrandom (LP: #1891403)
  * debian/testsuite-xfail-debian.mk: XFAIL new tst-support_descriptors

  [ Thadeu Lima de Souza Cascardo ]
  * tests: Make preadwritev2 invalid flags tests unsupported (LP: #1770480)

  [ Andreas Hasenack ]
  * branch-pthread_rwlock_trywrlock-hang-23844.patch:
    nptl: Fix pthread_rwlock_try*lock stalls (Bug 23844) (LP: #1864864)

 -- Balint Reczey <email address hidden> Wed, 02 Sep 2020 11:18:37 +0200