tree 5dbbaa64f3b99f6340475b25b58e0cd0d27b70b1
parent a5c24552354ff1e35bb4022ebc0b791eb7882b04
author Davidlohr Bueso <dave@stgolabs.net> 1639160458 -0800
committer Jens Axboe <axboe@kernel.dk> 1639160767 -0700

block: fix ioprio_get(IOPRIO_WHO_PGRP) vs setuid(2)

do_each_pid_thread(PIDTYPE_PGID) can race with a concurrent
change_pid(PIDTYPE_PGID) that can move the task from one hlist
to another while iterating. Serialize ioprio_get to take
the tasklist_lock in this case, just like it's set counterpart.

Fixes: d69b78ba1de (ioprio: grab rcu_read_lock in sys_ioprio_{set,get}())
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Link: https://lore.kernel.org/r/20211210182058.43417-1-dave@stgolabs.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>