From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73F8AC433E3 for ; Mon, 17 Aug 2020 18:35:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5752E2063A for ; Mon, 17 Aug 2020 18:35:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597689356; bh=ebDReBXON6r/dYIuzaxLcyZBV47Ar2EBxcl3ETii/CA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2DwmU8uXav65OlNBHlYTU5Qk/3SRKUMqu36qGypB4SnF+lHNJzYvp2cV8BRgpte+Z OliRFOZZcd9PtBIWZ7DnLosQezEkiN3t//2s45vykJexWqnKq1oC1bmvmp22fMycHA yZtq9TQhTp/L3aPhDwbc0MqVxfIDAxx+AQHaH89M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391165AbgHQSfx (ORCPT ); Mon, 17 Aug 2020 14:35:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:46922 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730976AbgHQP7k (ORCPT ); Mon, 17 Aug 2020 11:59:40 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2544C20888; Mon, 17 Aug 2020 15:59:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597679979; bh=ebDReBXON6r/dYIuzaxLcyZBV47Ar2EBxcl3ETii/CA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q2RHcG9SV27bICgVgxax1XOwCtmOulhVWDgDTeJ2oV2z9wNK35WfQ94HI3+cJql2R zut3wpjFltaKywAJpqPiuxFHJbS3uux7gOZI5UO4lH2FGHD4EejUmEGf/Uopfd3gdQ wEsiV5NkQ85XEX3QqPDV/4/nGlu71l0bJeEbQUog= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+9b260fc33297966f5a8e@syzkaller.appspotmail.com, Jens Axboe Subject: [PATCH 5.7 393/393] io_uring: hold ctx reference around task_work queue + execute Date: Mon, 17 Aug 2020 17:17:23 +0200 Message-Id: <20200817143838.652346152@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143819.579311991@linuxfoundation.org> References: <20200817143819.579311991@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jens Axboe commit 6d816e088c359866f9867057e04f244c608c42fe upstream. We're holding the request reference, but we need to go one higher to ensure that the ctx remains valid after the request has finished. If the ring is closed with pending task_work inflight, and the given io_kiocb finishes sync during issue, then we need a reference to the ring itself around the task_work execution cycle. Cc: stable@vger.kernel.org # v5.7+ Reported-by: syzbot+9b260fc33297966f5a8e@syzkaller.appspotmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/io_uring.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4214,6 +4214,8 @@ static int __io_async_wake(struct io_kio tsk = req->task; req->result = mask; init_task_work(&req->task_work, func); + percpu_ref_get(&req->ctx->refs); + /* * If this fails, then the task is exiting. When a task exits, the * work gets canceled, so just cancel this request as well instead @@ -4313,6 +4315,7 @@ static void io_poll_task_handler(struct static void io_poll_task_func(struct callback_head *cb) { struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); + struct io_ring_ctx *ctx = req->ctx; struct io_kiocb *nxt = NULL; io_poll_task_handler(req, &nxt); @@ -4323,6 +4326,7 @@ static void io_poll_task_func(struct cal __io_queue_sqe(nxt, NULL); mutex_unlock(&ctx->uring_lock); } + percpu_ref_put(&ctx->refs); } static int io_poll_double_wake(struct wait_queue_entry *wait, unsigned mode, @@ -4439,6 +4443,7 @@ static void io_async_task_func(struct ca if (io_poll_rewait(req, &apoll->poll)) { spin_unlock_irq(&ctx->completion_lock); + percpu_ref_put(&ctx->refs); return; } @@ -4476,6 +4481,7 @@ end_req: kfree(apoll->double_poll); kfree(apoll); + percpu_ref_put(&ctx->refs); } static int io_async_wake(struct wait_queue_entry *wait, unsigned mode, int sync,