From: Pavel Begunkov Date: Mon, 26 Sep 2022 23:44:39 +0000 (+0100) Subject: io_uring/rw: fix unexpected link breakage X-Git-Tag: v6.1-rc1~135^2~8 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bf68b5b34311ee57ed40749a1257a30b46127556;p=thirdparty%2Flinux.git io_uring/rw: fix unexpected link breakage req->cqe.res is set in io_read() to the amount of bytes left to be done, which is used to figure out whether to fail a read or not. However, io_read() may do another without returning, and we stash the previous value into ->bytes_done but forget to update cqe.res. Then we ask a read to do strictly less than cqe.res but expect the return to be exactly cqe.res. Fix the bug by updating cqe.res for retries. Cc: stable@vger.kernel.org Reported-and-Tested-by: Beld Zhang Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/3a1088440c7be98e5800267af922a67da0ef9f13.1664235732.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- diff --git a/io_uring/rw.c b/io_uring/rw.c index 59c92a4616b88..ed14322aadb90 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -793,6 +793,7 @@ int io_read(struct io_kiocb *req, unsigned int issue_flags) return -EAGAIN; } + req->cqe.res = iov_iter_count(&s->iter); /* * Now retry read with the IOCB_WAITQ parts set in the iocb. If * we get -EIOCBQUEUED, then we'll get a notification when the