generate systemd invalid memory address panic

[jtligon]

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

/kind bug

Description

I've managed to get a container up and running with a device passed in. Now I'm trying to generate a systemd unit so thiat it will start the container when I power cycle to box. running podman generate systemd ... gives me the error pasted below.

Steps to reproduce the issue:

1. Start a container named motioneye

2. sudo podman generate systemd motioneye -f --restart-policy restart-always

3. boom

Describe the results you received:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x56382de2c04d]

goroutine 1 [running]:
panic(0x56382e3f4a60, 0x56382f3f3750)
	/usr/lib/golang/src/runtime/panic.go:1064 +0x471 fp=0xc000595b98 sp=0xc000595ae0 pc=0x56382cc52301
runtime.panicmem(...)
	/usr/lib/golang/src/runtime/panic.go:212
runtime.sigpanic()
	/usr/lib/golang/src/runtime/signal_unix.go:695 +0x3de fp=0xc000595bc8 sp=0xc000595b98 pc=0x56382cc6964e
github.com/containers/libpod/cmd/podman/generate.systemd(0x56382f411c60, 0xc0001b7e40, 0x1, 0x4, 0x0, 0x0)
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/cmd/podman/generate/systemd.go:58 +0x15d fp=0xc000595c88 sp=0xc000595bc8 pc=0x56382de2c04d
github.com/containers/libpod/vendor/github.com/spf13/cobra.(*Command).execute(0x56382f411c60, 0xc0001ae030, 0x4, 0x4, 0x56382f411c60, 0xc0001ae030)
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/vendor/github.com/spf13/cobra/command.go:838 +0x455 fp=0xc000595d60 sp=0xc000595c88 pc=0x56382d647455
github.com/containers/libpod/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0x56382f420360, 0xc0001a8020, 0x56382e3f1a60, 0x56382f4c9388)
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/vendor/github.com/spf13/cobra/command.go:943 +0x319 fp=0xc000595e38 sp=0xc000595d60 pc=0x56382d647f59
github.com/containers/libpod/vendor/github.com/spf13/cobra.(*Command).Execute(...)
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/vendor/github.com/spf13/cobra/command.go:883
github.com/containers/libpod/vendor/github.com/spf13/cobra.(*Command).ExecuteContext(...)
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/vendor/github.com/spf13/cobra/command.go:876
main.Execute()
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/cmd/podman/root.go:91 +0xee fp=0xc000595eb8 sp=0xc000595e38 pc=0x56382df02a8e
main.main()
	/builddir/build/BUILD/podman-2.0.4/_build/src/github.com/containers/libpod/cmd/podman/main.go:68 +0x18e fp=0xc000595f88 sp=0xc000595eb8 pc=0x56382df024ae
runtime.main()
	/usr/lib/golang/src/runtime/proc.go:203 +0x202 fp=0xc000595fe0 sp=0xc000595f88 pc=0x56382cc54d82
runtime.goexit()
	/usr/lib/golang/src/runtime/asm_amd64.s:1373 +0x1 fp=0xc000595fe8 sp=0xc000595fe0 pc=0x56382cc83e61

Describe the results you expected:
I expected

Additional information you deem important (e.g. issue happens only occasionally):

Output of podman version:

Version:      2.0.4
API Version:  1
Go Version:   go1.14.6
Built:        Wed Dec 31 19:00:00 1969
OS/Arch:      linux/amd64

Output of podman info --debug:

host:
  arch: amd64
  buildahVersion: 1.15.0
  cgroupVersion: v2
  conmon:
    package: conmon-2.0.19-1.fc32.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.0.19, commit: 5dce9767526ed27f177a8fa3f281889ad509fea7'
  cpus: 4
  distribution:
    distribution: fedora
    version: "32"
  eventLogger: file
  hostname: fitlet2
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 5.7.10-201.fc32.x86_64
  linkmode: dynamic
  memFree: 608137216
  memTotal: 8155160576
  ociRuntime:
    name: crun
    package: crun-0.14.1-1.fc32.x86_64
    path: /usr/bin/crun
    version: |-
      crun version 0.14.1
      commit: 598ea5e192ca12d4f6378217d3ab1415efeddefa
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +YAJL
  os: linux
  remoteSocket:
    path: /run/user/1000/podman/podman.sock
  rootless: true
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.1.4-1.fc32.x86_64
    version: |-
      slirp4netns version 1.1.4
      commit: b66ffa8e262507e37fca689822d23430f3357fe8
      libslirp: 4.3.1
      SLIRP_CONFIG_VERSION_MAX: 2
  swapFree: 3204444160
  swapTotal: 3204444160
  uptime: 111h 32m 40.47s (Approximately 4.62 days)
registries:
  search:
  - registry.fedoraproject.org
  - registry.access.redhat.com
  - registry.centos.org
  - docker.io
store:
  configFile: /home/jligon/.config/containers/storage.conf
  containerStore:
    number: 0
    paused: 0
    running: 0
    stopped: 0
  graphDriverName: overlay
  graphOptions:
    overlay.mount_program:
      Executable: /usr/bin/fuse-overlayfs
      Package: fuse-overlayfs-1.1.2-1.fc32.x86_64
      Version: |-
        fusermount3 version: 3.9.1
        fuse-overlayfs: version 1.1.0
        FUSE library version 3.9.1
        using FUSE kernel interface version 7.31
  graphRoot: /home/jligon/.local/share/containers/storage
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "false"
  imageStore:
    number: 1
  runRoot: /run/user/1000/containers
  volumePath: /home/jligon/.local/share/containers/storage/volumes
version:
  APIVersion: 1
  Built: 0
  BuiltTime: Wed Dec 31 19:00:00 1969
  GitCommit: ""
  GoVersion: go1.14.6
  OsArch: linux/amd64
  Version: 2.0.4

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

podman-2.0.4-1.fc32.x86_64

Additional environment details (AWS, VirtualBox, physical, etc.):

Linux fitlet2 5.7.10-201.fc32.x86_64 #1 SMP Thu Jul 23 00:58:39 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

[vrothberg]

Thanks for opening the issue, @jtligon! I'll wrap up a fix.

[vrothberg]

@jtligon, to unblock your work: use "always" instead of "restart-always".

[jtligon]

looks great!
tyvm sir!

/home/jligon/container-2193796636fdba68b7c869be05ae35bb3bb47f92ac2b1b2193424aa9f705dd23.service

panic still needs cleaning up, i assume.

[vrothberg]

Awesome!

Here's a PR to fix the issue: #7272