From: Pavel Begunkov asml.silence@gmail.com
commit 46fee9ab02cb24979bbe07631fc3ae95ae08aa3e upstream.
__io_queue_proc() can enqueue both poll entries and still fail afterwards, so the callers trying to cancel it should also try to remove the second poll entry (if any).
For example, it may leave the request alive referencing a io_uring context but not accessible for cancellation:
[ 282.599913][ T1620] task:iou-sqp-23145 state:D stack:28720 pid:23155 ppid: 8844 flags:0x00004004 [ 282.609927][ T1620] Call Trace: [ 282.613711][ T1620] __schedule+0x93a/0x26f0 [ 282.634647][ T1620] schedule+0xd3/0x270 [ 282.638874][ T1620] io_uring_cancel_generic+0x54d/0x890 [ 282.660346][ T1620] io_sq_thread+0xaac/0x1250 [ 282.696394][ T1620] ret_from_fork+0x1f/0x30
Cc: stable@vger.kernel.org Fixes: 18bceab101add ("io_uring: allow POLL_ADD with double poll_wait() users") Reported-and-tested-by: syzbot+ac957324022b7132accf@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/0ec1228fc5eda4cb524eeda857da8efdc43c331c.162677445... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/io_uring.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5121,6 +5121,8 @@ static __poll_t __io_arm_poll_handler(st ipt->error = -EINVAL;
spin_lock_irq(&ctx->completion_lock); + if (ipt->error) + io_poll_remove_double(req); if (likely(poll->head)) { spin_lock(&poll->head->lock); if (unlikely(list_empty(&poll->wait.entry))) {