FAILED: patch "[PATCH] io_uring: fix leaks on IOPOLL and CQE_SKIP" failed to apply to 5.17-stable tree

The patch below does not apply to the 5.17-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c0713540f6d55c53dca65baaead55a5a8b20552d Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <[email protected]>
Date: Sun, 17 Apr 2022 10:10:34 +0100
Subject: [PATCH] io_uring: fix leaks on IOPOLL and CQE_SKIP

If all completed requests in io_do_iopoll() were marked with REQ_F_CQE_SKIP, we'll not only skip CQE posting but also io_free_batch_list() leaking memory and resources.

Move @nr_events increment before REQ_F_CQE_SKIP check. We'll potentially return the value greater than the real one, but iopolling will deal with it and the userspace will re-iopoll if needed. In anyway, I don't think there are many use cases for REQ_F_CQE_SKIP + IOPOLL.

index 24409dd07239..7625b29153b9 100644
@@ -2797,11 +2797,10 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
 		/* order with io_complete_rw_iopoll(), e.g. ->result updates */
 		if (!smp_load_acquire(&req->iopoll_completed))
 			break;
+		nr_events++;
 		if (unlikely(req->flags & REQ_F_CQE_SKIP))
 			continue;
-
 		__io_fill_cqe_req(req, req->result, io_put_kbuf(req, 0));
-		nr_events++;
 	}
 
 	if (unlikely(!nr_events))

Here's one for 5.17.

From c0713540f6d55c53dca65baaead55a5a8b20552d Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <[email protected]>
Date: Sun, 17 Apr 2022 10:10:34 +0100
Subject: [PATCH] io_uring: fix leaks on IOPOLL and CQE_SKIP

io_uring: fix leaks on IOPOLL and CQE_SKIP

commit c0713540f6d55c53dca65baaead55a5a8b20552d upstream.

If all completed requests in io_do_iopoll() were marked with REQ_F_CQE_SKIP, we'll not only skip CQE posting but also io_free_batch_list() leaking memory and resources.

Move @nr_events increment before REQ_F_CQE_SKIP check. We'll potentially return the value greater than the real one, but iopolling will deal with it and the userspace will re-iopoll if needed. In anyway, I don't think there are many use cases for REQ_F_CQE_SKIP + IOPOLL.

index 619c67fd456d..26756101437d 100644
@@ -2612,11 +2612,10 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
 		/* order with io_complete_rw_iopoll(), e.g. ->result updates */
 		if (!smp_load_acquire(&req->iopoll_completed))
 			break;
+		nr_events++;
 		if (unlikely(req->flags & REQ_F_CQE_SKIP))
 			continue;
-
 		__io_fill_cqe(ctx, req->user_data, req->result, io_put_kbuf(req));
-		nr_events++;
 	}
 
 	if (unlikely(!nr_events))

Jens Axboe

Now queued up, thanks!

greg k-h