[Bug 1874824] Re: pgrep reports error "cannot allocate" when run without stack limit

[William Wilson]

The verification passed for focal:

jawn-smith at focal-vm:~$ apt-cache policy procps
procps:
  Installed: 2:3.3.16-1ubuntu2
  Candidate: 2:3.3.16-1ubuntu2.1
  Version table:
     2:3.3.16-1ubuntu2.1 500
        500 http://us.archive.ubuntu.com/ubuntu focal-proposed/main amd64 Packages
 *** 2:3.3.16-1ubuntu2 500
        500 http://us.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status
jawn-smith at focal-vm:~$ ulimit -S -s unlimited
jawn-smith at focal-vm:~$ pgrep bash
pgrep: cannot allocate 4611686018427387903 bytes
jawn-smith at focal-vm:~$ sudo apt install procps
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
  procps
1 upgraded, 0 newly installed, 0 to remove and 64 not upgraded.
Need to get 233 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://us.archive.ubuntu.com/ubuntu focal-proposed/main amd64 procps amd64 2:3.3.16-1ubuntu2.1 [233 kB]
Fetched 233 kB in 0s (613 kB/s)
(Reading database ... 184500 files and directories currently installed.)
Preparing to unpack .../procps_2%3a3.3.16-1ubuntu2.1_amd64.deb ...
Unpacking procps (2:3.3.16-1ubuntu2.1) over (2:3.3.16-1ubuntu2) ...
Setting up procps (2:3.3.16-1ubuntu2.1) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for systemd (245.4-4ubuntu3.6) ...
jawn-smith at focal-vm:~$ ulimit -S -s unlimited
jawn-smith at focal-vm:~$ pgrep bash
1744
jawn-smith at focal-vm:~$


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

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https://bugs.launchpad.net/bugs/1874824

Title:
  pgrep reports error "cannot allocate" when run without stack limit

Status in procps package in Ubuntu:
  Fix Released
Status in procps source package in Focal:
  Fix Committed
Status in procps source package in Groovy:
  Fix Committed
Status in procps source package in Hirsute:
  Fix Released
Status in procps package in Debian:
  New

Bug description:
  [Impact]

    - Users who have ulimit set high would see either slow
      or failed pgrep and pkill commands
    - Users who have ulimit set to unlimited would see
      failed pgrep and pkill commands
    - This bug occurs because the behavior of sysconf(_SC_ARG_MAX)
      changed with a newer version of the kernel.

  [Test Case]

    - set the ulimit to unlimited by running `ulimit -S -s unlimited`
    - run `pgrep bash` to see that the "cannot allocate" error is
       printed and the command has failed.

  [Where Problems Could Occur]

    - We have set upper and lower limits on the size of the malloc, but
      if further kernel versions break the call to sysconf in
      unexpected ways we could still see problems.

  [Original Description]

  If you have no stack limit (ulimit -S -s unlimited), any pgrep call
  will fail with an error:

  > pgrep vim
  pgrep: cannot allocate 4611686018427387903 bytes

  If you have a high stack limit (e.g. ulimit -S -s 500000), pgrep is
  very slow:

  > time pgrep vim
  2196
  real 8.48s user 8.40s syst 0.07s busy 99% rmem 253444

  The relevant upstream bug report could be: https://gitlab.com/procps-ng/procps/-/issues/152
  Archlinux bug report: https://bugs.archlinux.org/task/66093

  procps:
    Installed: 2:3.3.16-1ubuntu2
    500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages

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