This is a note to let you know that I've just added the patch titled io_uring: fix leaks on IOPOLL and CQE_SKIP to the 5.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: io_uring-fix-leaks-on-iopoll-and-cqe_skip.patch and it can be found in the queue-5.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From c0713540f6d55c53dca65baaead55a5a8b20552d Mon Sep 17 00:00:00 2001 From: Pavel Begunkov <asml.silence@xxxxxxxxx> Date: Sun, 17 Apr 2022 10:10:34 +0100 Subject: io_uring: fix leaks on IOPOLL and CQE_SKIP From: Pavel Begunkov <asml.silence@xxxxxxxxx> 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. Fixes: 83a13a4181b0e ("io_uring: tweak iopoll CQE_SKIP event counting") Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> Link: https://lore.kernel.org/r/5072fc8693fbfd595f89e5d4305bfcfd5d2f0a64.1650186611.git.asml.silence@xxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2612,11 +2612,10 @@ static int io_do_iopoll(struct io_ring_c /* 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)) Patches currently in stable-queue which might be from asml.silence@xxxxxxxxx are queue-5.17/io_uring-fix-leaks-on-iopoll-and-cqe_skip.patch