This is caused do a change made upstream in the 4.11 kernel, which forbids writing the buffer size parameter after boot. The change to boot time preallocated work buffers made this parameter useless, but 4.11 only partially merged that work, making writing the buffer size an attack vector on the kernel memory and with user namespaces enabled any user could exploit it. Hence a follow-on patch to make the buffer size read-only after boot.
We have 2 choices for dealing with this, either fix the regression tests OR we can virtualize the buffer size parameter per namespace, capping the virtualized size by what was allocated at boot. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apparmor in Ubuntu. https://bugs.launchpad.net/bugs/1692543 Title: Regression tests cannot write to apparmor path_max module parameter in artful/4.11 Status in apparmor package in Ubuntu: New Bug description: The longpath regression tests tries to write to /sys/module/apparmor/parameters/path_max, but this is read-only in artful/4.11: commit cdc8e09e16bb7eb7d23fcbdbe416aa91770fb4d6 Author: John Johansen <john.johan...@canonical.com> Date: Thu Apr 6 05:14:20 2017 -0700 apparmor: Make path_max parameter readonly This is causing ADT to fail. https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac /autopkgtest-artful-canonical-kernel-team- ppa/artful/amd64/l/linux/20170519_170900_9130b@/log.gz running longpath longpath.sh: line 53: /sys/module/apparmor/parameters/path_max: Permission denied Fatal Error (longpath): Unexpected shell error. Run with -x to debug To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/1692543/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
