[Bug 1637026] Re: kill incorrectly parses negative PIDs

[dann frazier]

root at procpstest:~# strace -f -o /tmp/strace.out su dannf -c '/bin/kill -12'
root at procpstest:~# grep kill /tmp/strace.out 
2623  execve("/bin/su", ["su", "dannf", "-c", "/bin/kill -12"], [/* 11 vars */]) = 0
2628  execve("/bin/bash", ["bash", "-c", "/bin/kill -12"], [/* 17 vars */]) = 0
2628  execve("/bin/kill", ["/bin/kill", "-12"], [/* 17 vars */]) = 0
2628  kill(-12, SIGUSR2)                = -1 ESRCH (No such process)
root at procpstest:~# 

** Tags removed: verification-needed
** Tags added: verification-done

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https://bugs.launchpad.net/bugs/1637026

Title:
  kill incorrectly parses negative PIDs

Status in procps package in Ubuntu:
  Fix Released
Status in procps source package in Xenial:
  Fix Committed

Bug description:
  [Impact]
  When kill is called with a negative argument, incorrect parsing can lead it to call sys_kill(-1), thus sending a signal to all permitted processes on the system. A couple of users have hit this while deploying Hadoop, which seems to tickle this - basically killing everything on the system.

  [Test Case]
  Though I don't know what Hadoop is calling, here's a couple of ways to trigger this:

  One possibility is if kill were called w/ a numeric signal that
  happened to start with a '1' and while omitting the required <pid>
  argument:

  kill -12

  Another would be to specify a numeric signal (that again happened to
  start with a 1) multiple times:
  kill -13 -13 12345

  [Regression Risk]
  This is a backport from upstream that is already available in 16.10, with no known regressions.

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