diff options
| author | Jens Axboe <axboe@kernel.dk> | 2023-06-13 19:26:55 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-06-14 12:54:55 -0600 |
| commit | adeaa3f290ecf7f6a6a5c53219a4686cbdff5fbd (patch) | |
| tree | 594103ff2751e9f571323f6cd21eb2ab1f757a65 | |
| parent | cac9e4418f4cbd548ccb065b3adcafe073f7f7d2 (diff) | |
io_uring/io-wq: clear current->worker_private on exit
A recent fix stopped clearing PF_IO_WORKER from current->flags on exit,
which meant that we can now call inc/dec running on the worker after it
has been removed if it ends up scheduling in/out as part of exit.
If this happens after an RCU grace period has passed, then the struct
pointed to by current->worker_private may have been freed, and we can
now be accessing memory that is freed.
Ensure this doesn't happen by clearing the task worker_private field.
Both io_wq_worker_running() and io_wq_worker_sleeping() check this
field before going any further, and we don't need any accounting etc
done after this worker has exited.
Fixes: fd37b884003c ("io_uring/io-wq: don't clear PF_IO_WORKER on exit")
Reported-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/io-wq.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index fe38eb0cbc82..399e9a15c38d 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -220,7 +220,12 @@ static void io_worker_exit(struct io_worker *worker) list_del_rcu(&worker->all_list); raw_spin_unlock(&wq->lock); io_wq_dec_running(worker); - worker->flags = 0; + /* + * this worker is a goner, clear ->worker_private to avoid any + * inc/dec running calls that could happen as part of exit from + * touching 'worker'. + */ + current->worker_private = NULL; kfree_rcu(worker, rcu); io_worker_ref_put(wq); |