Commit 23fffb2f authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring/cancel: re-grab ctx mutex after finishing wait 



If we have a signal pending during cancelations, it'll cause the
task_work run to return an error. Since we didn't run task_work, the
current task is left in TASK_INTERRUPTIBLE state when we need to
re-grab the ctx mutex, and the kernel will rightfully complain about
that.

Move the lock grabbing for the error cases outside the loop to avoid
that issue.

Reported-by: default avatar <syzbot+7df055631cd1be4586fd@syzkaller.appspotmail.com>
Link: https://lore.kernel.org/io-uring/0000000000003a14a905f05050b0@google.com/


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 52ea806a

io_uring/cancel.c

+4 −5
Original line number Diff line number Diff line
@@ -288,24 +288,23 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) 


		ret = __io_sync_cancel(current->io_uring, &cd, sc.fd);



		mutex_unlock(&ctx->uring_lock);

		if (ret != -EALREADY)

			break;



		mutex_unlock(&ctx->uring_lock);

		ret = io_run_task_work_sig(ctx);

		if (ret < 0) {

			mutex_lock(&ctx->uring_lock);

		if (ret < 0)

			break;

		}

		ret = schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS);

		mutex_lock(&ctx->uring_lock);

		if (!ret) {

			ret = -ETIME;

			break;

		}

		mutex_lock(&ctx->uring_lock);

	} while (1);



	finish_wait(&ctx->cq_wait, &wait);

	mutex_lock(&ctx->uring_lock);



	if (ret == -ENOENT || ret > 0)

		ret = 0;