Hi Eric! A few days ago we've noticed that our zombie00 test case started failing: https://ci.openvz.org/job/CRIU/view/All/job/CRIU-linux-next/406/console --- ======================== Run zdtm/static/zombie00 in h ========================= Start test ./zombie00 --pidfile=zombie00.pid --outfile=zombie00.out Run criu dump Run criu restore Send the 15 signal to 30 Wait for zdtm/static/zombie00(30) to die for 0.100000 ################ Test zdtm/static/zombie00 FAIL at result check ################
I've narrowed problem down to commit | From ce99dd5fd5f600f9f4f0d37bb8847c1cb7c6e4fc Mon Sep 17 00:00:00 2001 | From: "Eric W. Biederman" <[email protected]> | Date: Thu, 13 Oct 2016 21:23:16 -0500 | Subject: [PATCH] mm: Add a user_ns owner to mm_struct and fix | ptrace_may_access | | During exec dumpable is cleared if the file that is being executed is | not readable by the user executing the file. A bug in | ptrace_may_access allows reading the file if the executable happens to | enter into a subordinate user namespace (aka clone(CLONE_NEWUSER), | unshare(CLONE_NEWUSER), or setns(fd, CLONE_NEWUSER). and the reason is that the zombie tasks do not have task::mm and in resut we're obtaining -EPERM when trying to read task->exit_code from /proc/pid/stat. Looking into commit I suspect when mm = NULL we've to move back the test ptrace_has_cap(__task_cred(task)->user_ns, mode)?
