[Bug 1691491] [NEW] lookbehind broken

[Matt Chesler]

Public bug reported:

Trying to troubleshoot unexpected behavior with haproxy, I discovered
that lookbehind appears to be broken in version 1:8.31-2ubuntu2.3 of the
libpcre3 package.

I have an haproxy rule to rewrite URL paths that do not begin with
"build" or "static":

reqirep ^([^\ :]*)\ /(?!build|static).*\ (.*) \1\ /index.html\ \2

With the latest version of libpcre3 installed (1:8.31-2ubuntu2.3), this
line matches all requests.  If I downgrade to 1:8.31-2ubuntu2.2 and
restart haproxy, the rule correctly matches only paths that do not start
with "static" or "build".

$ lsb_release -rd
Description:	Ubuntu 14.04.4 LTS
Release:	14.04

$ apt-cache policy libpcre3
libpcre3:
  Installed: 1:8.31-2ubuntu2.3
  Candidate: 1:8.31-2ubuntu2.3
  Version table:
 *** 1:8.31-2ubuntu2.3 0
        500 http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:8.31-2ubuntu2.2 0
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
     1:8.31-2ubuntu2 0
        500 http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

** Affects: pcre3 (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1691491

Title:
  lookbehind broken

Status in pcre3 package in Ubuntu:
  New

Bug description:
  Trying to troubleshoot unexpected behavior with haproxy, I discovered
  that lookbehind appears to be broken in version 1:8.31-2ubuntu2.3 of
  the libpcre3 package.

  I have an haproxy rule to rewrite URL paths that do not begin with
  "build" or "static":

  reqirep ^([^\ :]*)\ /(?!build|static).*\ (.*) \1\ /index.html\ \2

  With the latest version of libpcre3 installed (1:8.31-2ubuntu2.3),
  this line matches all requests.  If I downgrade to 1:8.31-2ubuntu2.2
  and restart haproxy, the rule correctly matches only paths that do not
  start with "static" or "build".

  $ lsb_release -rd
  Description:	Ubuntu 14.04.4 LTS
  Release:	14.04

  $ apt-cache policy libpcre3
  libpcre3:
    Installed: 1:8.31-2ubuntu2.3
    Candidate: 1:8.31-2ubuntu2.3
    Version table:
   *** 1:8.31-2ubuntu2.3 0
          500 http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       1:8.31-2ubuntu2.2 0
          500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
       1:8.31-2ubuntu2 0
          500 http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

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