Bug#952609: libc6: pthread_rwlock_trywrlock hangs

[Aurelien Jarno]

On 2020-02-26 17:07, Ondřej Surý wrote:
> Package: libc6
> Version: 2.28-10
> Severity: important
> Tags: upstream patch
> 
> -BEGIN PGP SIGNED MESSAGE-
> Hash: SHA512
> 
> Dear Maintainer,
> 
> glibc after 2.26 (included) and before 2.30 hangs in pthread_rwlock_tryrwlock
> and pthread_rwlock_tryrdlock, the details and test cases can be found in
> https://sourceware.org/bugzilla/show_bug.cgi?id=23844#c14
> 
> This especially hits BIND 9.16 when using pthread_rwlock (instead of custom 
> ISC
> rwlock).
> 
> So, could you please fix this in buster?  For sid, this will get fixed as part
> of regular updated to 2.30,

This patch is already included since glibc 2.28-8 as part of pulling the
upstream stable branch. So it should already be fixed in buster, bullseye
and sid.

At least I confirm that the bug23844.wr.c testcase from the upstream bug
report sometimes fail with glibc 2.28-7, but never fails with glibc
2.28-8.

Regards,
Aurelien

-- 
Aurelien Jarno  GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net


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Bug#952609: libc6: pthread_rwlock_trywrlock hangs

[Ondřej Surý]

Package: libc6
Version: 2.28-10
Severity: important
Tags: upstream patch

-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

Dear Maintainer,

glibc after 2.26 (included) and before 2.30 hangs in pthread_rwlock_tryrwlock
and pthread_rwlock_tryrdlock, the details and test cases can be found in
https://sourceware.org/bugzilla/show_bug.cgi?id=23844#c14

This especially hits BIND 9.16 when using pthread_rwlock (instead of custom ISC
rwlock).

So, could you please fix this in buster?  For sid, this will get fixed as part
of regular updated to 2.30,

The patch is quite small and the impact of pthread_rwlock_try(rw|rd)lock()
hanging is pretty severe.  Also quite hard to find - we spent couple of days
hunting the bug in BIND 9 and it turned to be problem in glibc.

Thanks,
Ondrej

- -- System Information:
Debian Release: 10.3
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.19.0-8-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_IE.UTF-8, LC_CTYPE=en_IE.UTF-8 (charmap=UTF-8), 
LANGUAGE=en_IE:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

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