From: Jens Axboe axboe@kernel.dk
commit e6db6f9398dadcbc06318a133d4c44a2d3844e61 upstream.
We have two types of task_work based creation, one is using an existing worker to setup a new one (eg when going to sleep and we have no free workers), and the other is allocating a new worker. Only the latter should be freed when we cancel task_work creation for a new worker.
Fixes: af82425c6a2d ("io_uring/io-wq: free worker if task_work creation is canceled") Reported-by: syzbot+d56ec896af3637bdb7e4@syzkaller.appspotmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/io-wq.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -1230,7 +1230,12 @@ static void io_wq_cancel_tw_create(struc
worker = container_of(cb, struct io_worker, create_work); io_worker_cancel_cb(worker); - kfree(worker); + /* + * Only the worker continuation helper has worker allocated and + * hence needs freeing. + */ + if (cb->func == create_worker_cont) + kfree(worker); } }