Host's /dev/shm is mounted over when entering 14.10 and older sbuild schroots
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
schroot (Debian) |
Fix Released
|
Unknown
|
|||
schroot (Ubuntu) |
Fix Released
|
High
|
Tyler Hicks |
Bug Description
Originally reported by Scott Moser:
https:/
On a Vivid system with schroot 1.6.10-1ubuntu1, the host's /dev/shm is mounted over with a new tmpfs instance when entering a 14.10 and older schroot. It does not happen when entering a Vivid schroot.
# Create 14.10 and Vivid sbuild schroots
$ arch=amd64
$ for rel in vivid utopic; do mk-sbuild --eatmydata --arch=$arch $rel 2>&1 | tee /tmp/schroot-
# Enter vivid-amd64 sbuild schroot and diff /proc/self/mounts
$ mounts=
$ orig=$(mktemp) && cp $mounts $orig && schroot -c vivid-amd64 true; diff -u $orig $mounts
# Enter utopic-amd64 sbuild schroot and diff /proc/self/mounts
$ orig=$(mktemp) && cp $mounts $orig && schroot -c utopic-amd64 true; diff -u $orig $mounts
--- /tmp/tmp.DdnrDnkS2B 2015-03-31 18:19:51.406526006 -0500
+++ /proc/self/mounts 2015-03-31 18:19:51.818526006 -0500
@@ -28,3 +28,4 @@
tmpfs /run/user/108 tmpfs rw,nosuid,
gvfsd-fuse /run/user/108/gvfs fuse.gvfsd-fuse rw,nosuid,
tmpfs /run/user/1000 tmpfs rw,nosuid,
+tmpfs /dev/shm tmpfs rw,relatime 0 0
# Verify that /proc/self/mounts now contains two /dev/shm mounts
$ grep /dev/shm $mounts
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
tmpfs /dev/shm tmpfs rw,relatime 0 0
This causes a problem for programs that keep state in /dev/shm. For example, ecryptfs-utils maintains a per-user session counter in /dev/shm that is lost when a new tmpfs mount is performed on top of the old tmpfs mount. This results in encrypted home directories being unmounted when the schroot is tore down.
Changed in schroot (Ubuntu): | |
importance: | Undecided → High |
Changed in schroot (Ubuntu): | |
status: | New → Confirmed |
Changed in schroot (Ubuntu): | |
status: | Confirmed → In Progress |
assignee: | nobody → Tyler Hicks (tyhicks) |
Changed in schroot (Debian): | |
status: | Unknown → New |
Changed in schroot (Ubuntu): | |
status: | In Progress → Fix Committed |
Changed in schroot (Debian): | |
status: | New → Fix Released |
Note that this extra tmpfs mount happens with or without the use of encrypted home. It is more noticeable with encrypted home, since the encrypted home directory is unmounted.