segfault when LISTEN_PID and LISTEN_FDS are set but not LISTEN_FDNAMES

[eriksjolund]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description
A segmentation fault can be triggered by setting the environment variables
LISTEN_PID and LISTEN_FDS but not LISTEN_FDNAMES and then podman run ...

It seems the relevant code is

podman/pkg/rootless/rootless_linux.c

Line 314 in fe05956

saved_systemd_listen_fdnames = strdup(listen_fdnames);

Steps to reproduce the issue:

1. Create the file bug.bash with this content

   #!/bin/bash
   export LISTEN_PID=$$
   export LISTEN_FDS=1
   exec podman run --rm registry.fedoraproject.org/fedora:34 /bin/true
   

2. Run bash bug.sh

Describe the results you received:

Segmentation fault (core dumped)

Output of podman version:

Version:      3.2.0-dev
API Version:  3.2.0-dev
Go Version:   go1.15.3
Git Commit:   fe0595683a05c0f0307e07f0cce29f6ae0b3d310
Built:        Thu May 20 14:11:25 2021
OS/Arch:      linux/amd64

Output of podman info --debug | grep -v hostname::

host:
  arch: amd64
  buildahVersion: 1.20.2-dev
  cgroupManager: cgroupfs
  cgroupVersion: v1
  conmon:
    package: Unknown
    path: /var/data/podman-installations/build-podman_601505070e4cf66a37d42a81156e5508d0cfb79c__centos8__fe0595683a05c0f0307e07f0cce29f6ae0b3d310__v2.0.27__v0.9.1__1.15.3__0.19.1__v1.1.10__v1.5.0/bin/conmon
    version: 'conmon version 2.0.27, commit: 65fad4bfcb250df0435ea668017e643e7f462155'
  cpus: 8
  distribution:
    distribution: '"centos"'
    version: "8"
  eventLogger: journald
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 100
      size: 1
    - container_id: 1
      host_id: 231072
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1626
      size: 1
    - container_id: 1
      host_id: 231072
      size: 65536
  kernel: 4.18.0-240.22.1.el8_3.x86_64
  linkmode: dynamic
  memFree: 8183627776
  memTotal: 16600113152
  ociRuntime:
    name: crun
    package: Unknown
    path: /var/data/podman-installations/build-podman_601505070e4cf66a37d42a81156e5508d0cfb79c__centos8__fe0595683a05c0f0307e07f0cce29f6ae0b3d310__v2.0.27__v0.9.1__1.15.3__0.19.1__v1.1.10__v1.5.0/bin/crun
    version: |-
      crun version 0.19.1
      commit: 1535fedf0b83fb898d449f9680000f729ba719f5
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  remoteSocket:
    path: /run/user/1626/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: true
  serviceIsRemote: false
  slirp4netns:
    executable: /var/data/podman-installations/build-podman_601505070e4cf66a37d42a81156e5508d0cfb79c__centos8__fe0595683a05c0f0307e07f0cce29f6ae0b3d310__v2.0.27__v0.9.1__1.15.3__0.19.1__v1.1.10__v1.5.0/bin/slirp4netns
    package: Unknown
    version: |-
      slirp4netns version 1.1.10
      commit: baa2bc5ff12fe6db646c1f4f3f966526c0eba5a0
      libslirp: 4.5.0
      SLIRP_CONFIG_VERSION_MAX: 3
      libseccomp: 2.3.3
  swapFree: 8476684288
  swapTotal: 8476684288
  uptime: 869h 34m 7.95s (Approximately 36.21 days)
registries:
  search:
  - registry.access.redhat.com
  - registry.redhat.io
  - docker.io
store:
  configFile: /home/erik.sjolund/storage.conf
  containerStore:
    number: 3
    paused: 0
    running: 0
    stopped: 3
  graphDriverName: overlay
  graphOptions:
    overlay.mount_program:
      Executable: /var/data/podman-installations/build-podman_601505070e4cf66a37d42a81156e5508d0cfb79c__centos8__fe0595683a05c0f0307e07f0cce29f6ae0b3d310__v2.0.27__v0.9.1__1.15.3__0.19.1__v1.1.10__v1.5.0/bin/fuse-overlayfs
      Package: Unknown
      Version: |-
        fusermount3 version: 3.2.1
        fuse-overlayfs: version 1.5
        FUSE library version 3.4.1
        using FUSE kernel interface version 7.27
  graphRoot: /home/erik.sjolund/.local/share/containers/storage
  graphStatus:
    Backing Filesystem: xfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "false"
  imageStore:
    number: 1
  runRoot: /run/user/1626/containers
  volumePath: /home/erik.sjolund/.local/share/containers/storage/volumes
version:
  APIVersion: 3.2.0-dev
  Built: 1621512685
  BuiltTime: Thu May 20 14:11:25 2021
  GitCommit: fe0595683a05c0f0307e07f0cce29f6ae0b3d310
  GoVersion: go1.15.3
  OsArch: linux/amd64
  Version: 3.2.0-dev

Package info (e.g. output of rpm -q podman or apt list podman):

Podman was built in a GitHub Actions workflow and
downloaded from https://github.com/eriksjolund/build-podman/actions/runs/860325818