• Oleg Nesterov's avatar
    pids: make task_tgid_nr_ns() safe · dd1c1f2f
    Oleg Nesterov authored
    This was reported many times, and this was even mentioned in commit
    52ee2dfd ("pids: refactor vnr/nr_ns helpers to make them safe") but
    somehow nobody bothered to fix the obvious problem: task_tgid_nr_ns() is
    not safe because task->group_leader points to nowhere after the exiting
    task passes exit_notify(), rcu_read_lock() can not help.
    
    We really need to change __unhash_process() to nullify group_leader,
    parent, and real_parent, but this needs some cleanups.  Until then we
    can turn task_tgid_nr_ns() into another user of __task_pid_nr_ns() and
    fix the problem.
    Reported-by: 's avatarTroy Kensinger <tkensinger@google.com>
    Signed-off-by: 's avatarOleg Nesterov <oleg@redhat.com>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    dd1c1f2f