Crash when custom LXC path is passed

[Steve Naimoli]

Required information

• Distribution: RHEL
• Distribution version: 7
• The output of
  • lxc-start --version = 4.0.1
  • lxc-checkconfig
    --- Namespaces ---
    Namespaces: enabled
    Utsname namespace: enabled
    Ipc namespace: enabled
    Pid namespace: enabled
    User namespace: enabled
    Network namespace: enabled

--- Control groups ---
Cgroups: enabled

Cgroup v1 mount points:
/sys/fs/cgroup/systemd
/sys/fs/cgroup/net_cls,net_prio
/sys/fs/cgroup/perf_event
/sys/fs/cgroup/devices
/sys/fs/cgroup/pids
/sys/fs/cgroup/cpu,cpuacct
/sys/fs/cgroup/cpuset
/sys/fs/cgroup/freezer
/sys/fs/cgroup/blkio
/sys/fs/cgroup/debug
/sys/fs/cgroup/memory

Cgroup v2 mount points:

Cgroup v1 clone_children flag: enabled
Cgroup device: enabled
Cgroup sched: enabled
Cgroup cpu account: enabled
Cgroup memory controller: enabled
Cgroup cpuset: enabled

--- Misc ---
Veth pair device: enabled, not loaded
Macvlan: enabled, not loaded
Vlan: enabled, not loaded
Bridges: enabled, loaded
Advanced netfilter: enabled, not loaded
CONFIG_NF_NAT_IPV4: enabled, loaded
CONFIG_NF_NAT_IPV6: enabled, loaded
CONFIG_IP_NF_TARGET_MASQUERADE: enabled, loaded
CONFIG_IP6_NF_TARGET_MASQUERADE: enabled, not loaded
CONFIG_NETFILTER_XT_TARGET_CHECKSUM: enabled, loaded
CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled, not loaded
FUSE (for use with lxcfs): enabled, loaded

--- Checkpoint/Restore ---
checkpoint restore: enabled
CONFIG_FHANDLE: enabled
CONFIG_EVENTFD: enabled
CONFIG_EPOLL: enabled
CONFIG_UNIX_DIAG: enabled
CONFIG_INET_DIAG: enabled
CONFIG_PACKET_DIAG: enabled
CONFIG_NETLINK_DIAG: enabled
File capabilities:

Note : Before booting a new kernel, you can check its configuration
usage : CONFIG=/path/to/config /bin/lxc-checkconfig

• uname -a Linux proc1 4.9.98-rt76-7.5-#1 SMP PREEMPT Tue Apr 14 10:39:18 EDT 2020 x86_64 x86_64 x86_64 GNU/Linux

• cat /proc/self/cgroup
  11:memory:/user.slice
  10:debug:/
  9:blkio:/user.slice
  8:freezer:/
  7:cpuset:/
  6:cpu,cpuacct:/user.slice
  5:pids:/user.slice
  4:devices:/user.slice
  3:perf_event:/
  2:net_cls,net_prio:/
  1:name=systemd:/user.slice/user-1000.slice/session-2.scope

• cat /proc/1/mounts

sysfs /sys sysfs rw,seclabel,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
devtmpfs /dev devtmpfs rw,seclabel,nosuid,size=1995476k,nr_inodes=498869,mode=755 0 0
securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
tmpfs /dev/shm tmpfs rw,seclabel,nosuid,nodev,noexec 0 0
devpts /dev/pts devpts rw,seclabel,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,seclabel,nosuid,nodev,mode=755 0 0
tmpfs /sys/fs/cgroup tmpfs ro,seclabel,nosuid,nodev,noexec,mode=755 0 0
cgroup /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd 0 0
pstore /sys/fs/pstore pstore rw,seclabel,nosuid,nodev,noexec,relatime 0 0
cgroup /sys/fs/cgroup/net_cls,net_prio cgroup rw,nosuid,nodev,noexec,relatime,net_cls,net_prio 0 0
cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0
cgroup /sys/fs/cgroup/pids cgroup rw,nosuid,nodev,noexec,relatime,pids 0 0
cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpu,cpuacct 0 0
cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
cgroup /sys/fs/cgroup/debug cgroup rw,nosuid,nodev,noexec,relatime,debug 0 0
cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
/dev/mapper/vg1-lv_root / xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
systemd-1 /proc/sys/fs/binfmt_misc autofs rw,relatime,fd=33,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=5902 0 0
debugfs /sys/kernel/debug debugfs rw,seclabel,relatime 0 0
mqueue /dev/mqueue mqueue rw,seclabel,relatime 0 0
hugetlbfs /dev/hugepages hugetlbfs rw,seclabel,relatime 0 0
/dev/vda1 /boot xfs rw,seclabel,nosuid,nodev,relatime,attr2,inode64,noquota 0 0
/dev/mapper/vg1-lv_var /var xfs rw,seclabel,nosuid,nodev,relatime,attr2,inode64,noquota 0 0
/dev/mapper/vg1-lv_home /home xfs rw,seclabel,nosuid,nodev,relatime,attr2,inode64,noquota 0 0
/dev/mapper/vg1-lv_tmp /tmp xfs rw,seclabel,nosuid,nodev,noexec,relatime,attr2,inode64,noquota 0 0
/dev/mapper/vg1-lv_log /var/log xfs rw,seclabel,nosuid,nodev,relatime,attr2,inode64,noquota 0 0
/dev/mapper/vg1-lv_audit /var/log/audit xfs rw,seclabel,nosuid,nodev,noexec,relatime,attr2,inode64,noquota 0 0
sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0
lxcfs /var/lib/lxcfs fuse.lxcfs rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other 0 0
fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
tmpfs /var/lib/lxd/shmounts tmpfs rw,seclabel,relatime,size=100k,mode=711 0 0
tmpfs /var/lib/lxd/devlxd tmpfs rw,seclabel,relatime,size=100k,mode=755 0 0
tmpfs /run/user/1000 tmpfs rw,seclabel,nosuid,nodev,relatime,size=404504k,mode=700,uid=1000,gid=1000 0 0
gvfsd-fuse /run/user/1000/gvfs fuse.gvfsd-fuse rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0
/dev/fuse /run/user/1000/doc fuse rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0
tmpfs /run/user/0 tmpfs rw,seclabel,nosuid,nodev,relatime,size=404504k,mode=700 0 0
binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0

Issue description

lxc python API not accepting custom config_path; python bails with a Segmentation Fault. This is working in the C API.

[root@proc1 ~]# python
Python 2.7.5 (default, Sep 26 2019, 13:23:47)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

import lxc
c = lxc.Container("c1", "/containers/nodes")
Segmentation fault
[root@proc1 ~]#

Steps to reproduce

1. Create custom container path utilizing lxc commands at path : example /containers/nodes/
2. Verify Container node (ex. c1) has a config and rootfs in /containers/nodes/c1/
3. python
   import lxc
   c = lxc.Container("c1", "/containers/nodes")
4. Observe Segmentation Fault

[Stéphane Graber]

Moving to the correct project

[Steve Naimoli]

issue was on python2. python3 is operational.