OverlayFS: Wrong mnt_id and path reported in /proc in linux-3.13
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Confirmed
|
Medium
|
Unassigned |
Bug Description
I am running Ubuntu Trusty (3.13.0-65-generic #106-Ubuntu SMP Fri Oct 2 22:08:27 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux).
There are two issues in OverlayFS as follows:
1. /proc/<
2. /proc/<pid>/fd/<fd> shows incorrect path for the symlink target
These issues were previously reported and patched for the Ubuntu Vivid kernel (3.19) in bug #1479468, but the patch was not applied to the 3.13 kernel, possibly because it contains an older version of overlayfs.
These issues are now adversely affecting some versions of lxc when used in conjunction with the 3.13 kernel, because lxc has recently been patched to pass /proc/<pid>/fd/<fd> to the mount syscall. This change to lxc was made in response to cve-2015-1335; see bug #1476662.
The kernel issues cause some overlayfs-backed containers to fail to start, with error message,
strace: mount("
The mount fails because /proc/self/fd/16, which should point to a file in overlayfs, has an invalid value.
The version of lxc in the trusty-updates repository, lxc-1.0.
is not affected. The following versions of lxc are affected:
repository lxc version
-------
ppa:ubuntu-
ppa:ubuntu-
ppa:ubuntu-
To reproduce the lxc failure-to-start issue:
# Install the 3.13 kernel and also an affected version of lxc.
lxc-create -t download -n trusty -- -d ubuntu -r trusty -a amd64;
touch $HOME/test.txt;
echo "lxc.mount.entry = $HOME/test.txt home/ubuntu/
lxc-clone -s -B overlayfs trusty trusty_overlay;
lxc-start -n trusty_overlay; # fails to start
CVE References
description: | updated |
description: | updated |
tags: | removed: apparmor apport-collected third-party-packages |
Changed in linux (Ubuntu): | |
status: | Incomplete → Confirmed |
Changed in linux (Ubuntu): | |
importance: | Undecided → Medium |
Changed in linux (Ubuntu): | |
status: | Incomplete → Confirmed |
Changed in lxc (Ubuntu): | |
status: | Incomplete → Confirmed |
no longer affects: | lxc (Ubuntu) |
no longer affects: | lxc (Ubuntu) |
This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:
apport-collect 1507463
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.