From patchwork Sat May 11 17:08:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Stefan_B=C3=BChler?= X-Patchwork-Id: 10939785 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 647E515AB for ; Sat, 11 May 2019 17:08:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 537FE1FFFE for ; Sat, 11 May 2019 17:08:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 46A8E212D9; Sat, 11 May 2019 17:08:06 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,DKIM_ADSP_ALL, DKIM_INVALID,DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A7377212D9 for ; Sat, 11 May 2019 17:08:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727255AbfEKRID (ORCPT ); Sat, 11 May 2019 13:08:03 -0400 Received: from mail.stbuehler.de ([5.9.32.208]:54752 "EHLO mail.stbuehler.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725945AbfEKRID (ORCPT ); Sat, 11 May 2019 13:08:03 -0400 Received: from chromobil.fritz.box (unknown [IPv6:2a02:8070:a29c:5000:823f:5dff:fe0f:b5b6]) by mail.stbuehler.de (Postfix) with ESMTPSA id 75BE5C00A01; Sat, 11 May 2019 17:08:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=stbuehler.de; s=stbuehler1; t=1557594481; bh=UvzKPBgcb3z7tPf6cm2ZxLlr17a42KxrWBRpHJot+sY=; h=From:To:Subject:Date:In-Reply-To:References:From; b=pf0hs1ePKiTJs6q1kmvuupUsBfRXewdBsKuZfCuY4MU36KhLP73wAm7mxgRzJGBqJ mIotsmL21z+1LZcN6AvuKoiB9WUSawfLKC6G+PiWhBAMFTF5vvE93AjL7IZ/MfNaH6 2kes0Oi7GIIKocEsrbqCeT9kijRCb6/J6ym7cFvg= From: =?utf-8?q?Stefan_B=C3=BChler?= To: Jens Axboe , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH 1/1] io_uring: fix race condition reading SQE data Date: Sat, 11 May 2019 19:08:01 +0200 Message-Id: <20190511170801.32182-1-source@stbuehler.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <3900c9a9-41a2-31cb-3a7b-e93251505b15@kernel.dk> References: <3900c9a9-41a2-31cb-3a7b-e93251505b15@kernel.dk> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When punting to workers the SQE gets copied after the initial try. There is a race condition between reading SQE data for the initial try and copying it for punting it to the workers. For example io_rw_done calls kiocb->ki_complete even if it was prepared for IORING_OP_FSYNC (and would be NULL). The easiest solution for now is to alway prepare again in the worker. req->file is safe to prepare though as long as it is checked before use. Signed-off-by: Stefan Bühler --- fs/io_uring.c | 17 ++--------------- 1 file changed, 2 insertions(+), 15 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 48ea3977012a..576d9c652b4c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -329,9 +329,8 @@ struct io_kiocb { #define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */ #define REQ_F_FIXED_FILE 4 /* ctx owns file */ #define REQ_F_SEQ_PREV 8 /* sequential with previous */ -#define REQ_F_PREPPED 16 /* prep already done */ -#define REQ_F_IO_DRAIN 32 /* drain existing IO first */ -#define REQ_F_IO_DRAINED 64 /* drain done */ +#define REQ_F_IO_DRAIN 16 /* drain existing IO first */ +#define REQ_F_IO_DRAINED 32 /* drain done */ u64 user_data; u32 error; /* iopoll result from callback */ u32 sequence; @@ -896,9 +895,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, if (!req->file) return -EBADF; - /* For -EAGAIN retry, everything is already prepped */ - if (req->flags & REQ_F_PREPPED) - return 0; if (force_nonblock && !io_file_supports_async(req->file)) force_nonblock = false; @@ -941,7 +937,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, return -EINVAL; kiocb->ki_complete = io_complete_rw; } - req->flags |= REQ_F_PREPPED; return 0; } @@ -1227,16 +1222,12 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe) if (!req->file) return -EBADF; - /* Prep already done (EAGAIN retry) */ - if (req->flags & REQ_F_PREPPED) - return 0; if (unlikely(ctx->flags & IORING_SETUP_IOPOLL)) return -EINVAL; if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index)) return -EINVAL; - req->flags |= REQ_F_PREPPED; return 0; } @@ -1277,16 +1268,12 @@ static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe) if (!req->file) return -EBADF; - /* Prep already done (EAGAIN retry) */ - if (req->flags & REQ_F_PREPPED) - return 0; if (unlikely(ctx->flags & IORING_SETUP_IOPOLL)) return -EINVAL; if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index)) return -EINVAL; - req->flags |= REQ_F_PREPPED; return ret; }