> Do you have a testcase where restart doesn't work because of problems > with tty->pgrp restore? Or was this just something that caught your eye > during review? Yes, we faced this while trying to restore an Xvnc session (bash running a script + Xvnc + twm + xterm + bash). It was failing with -ESRCH at this particular point, and we have been trying to solve it. > Userspace can change h->tty_pgrp_owner to any value (bug, cosmic ray, > exploit attempt) before passing the checkpoint image to restart. We > don't want malicious programs to be able to cause an Oops or worse so we > need to make sure the index is less than the number of entries in the > pids_arr. Since the value was a prgrp id prior to this patch I doubt > that check already exists. Understood. It should be not if (h->tty_pgrp_owner != -1), but but if ( h->tty_pgrp_owner >=0 && h->tty_pgrp_owner < ctx->nr_tasks) > However, I suspect this is already covered in userspace > by rewriting the pids array prior to calling sys_restart(). See > ckpt_init_tree() in user-cr's restart.c and let me know if you agree > and/or see any problems with that approach. This may be indeed better, but it requires userspace to have knowledge about entire checkpoint structure, with (as far as I understand) is not the case currently, and may be hard to maintain while checkpoint format envolves in future. Nikita _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
