[Bug 2036420] [NEW] tzset generates ThreadSanitizer warnings if TZ not set

[Fredrik Arnerup]

Public bug reported:

A program that calls tzset (e.g. via mktime) from multiple threads will
generate ThreadSanitizer warnings, but only if the environment variable
TZ is not set. Please see attached example.

Not sure if it is a glibc bug or a limitation in ThreadSanitizer.

$ lsb_release -rd
Description:	Ubuntu 22.04.3 LTS
Release:	22.04

$ apt-cache policy libc6
libc6:
  Installed: 2.35-0ubuntu3.1
  Candidate: 2.35-0ubuntu3.1
  Version table:
 *** 2.35-0ubuntu3.1 500
        500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     2.35-0ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages

** Affects: glibc (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "Example code"
   https://bugs.launchpad.net/bugs/2036420/+attachment/5701793/+files/tzset_race.c

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https://bugs.launchpad.net/bugs/2036420

Title:
  tzset generates ThreadSanitizer warnings if TZ not set

Status in glibc package in Ubuntu:
  New

Bug description:
  A program that calls tzset (e.g. via mktime) from multiple threads
  will generate ThreadSanitizer warnings, but only if the environment
  variable TZ is not set. Please see attached example.

  Not sure if it is a glibc bug or a limitation in ThreadSanitizer.

  $ lsb_release -rd
  Description:	Ubuntu 22.04.3 LTS
  Release:	22.04

  $ apt-cache policy libc6
  libc6:
    Installed: 2.35-0ubuntu3.1
    Candidate: 2.35-0ubuntu3.1
    Version table:
   *** 2.35-0ubuntu3.1 500
          500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       2.35-0ubuntu3 500
          500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages

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