From patchwork Tue Jun 8 18:26:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 457552 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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 C35E1C4743F for ; Tue, 8 Jun 2021 19:14:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC86D610A2 for ; Tue, 8 Jun 2021 19:14:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235674AbhFHTQs (ORCPT ); Tue, 8 Jun 2021 15:16:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:36962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238343AbhFHTOq (ORCPT ); Tue, 8 Jun 2021 15:14:46 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id ECEEF61434; Tue, 8 Jun 2021 18:50:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623178223; bh=Q3LK4c37Lcc4PeoLN/dLINCVDg5mSVxY0TkKAzM5HDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PBPM0B3ZBX0+RyeQJjlSe8eCtoH87FPmnkDU0kTW9SW3jtltQ7tHZlZKzsKd1omvb 2MpVNbpNrfScbwoPM1paYxuNXjL3T3BL3/nnU8xNZBVCF0u6NUJoyRKeJ6uF30HnZG rb+KOWE4IIg4Uq/jqTIdxESLKXM2XMAHqAIBgDU0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Begunkov , Jens Axboe , Sasha Levin , syzbot+5a864149dd970b546223@syzkaller.appspotmail.com Subject: [PATCH 5.12 088/161] io_uring: fix ltout double free on completion race Date: Tue, 8 Jun 2021 20:26:58 +0200 Message-Id: <20210608175948.412603388@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210608175945.476074951@linuxfoundation.org> References: <20210608175945.476074951@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Pavel Begunkov [ Upstream commit 447c19f3b5074409c794b350b10306e1da1ef4ba ] Always remove linked timeout on io_link_timeout_fn() from the master request link list, otherwise we may get use-after-free when first io_link_timeout_fn() puts linked timeout in the fail path, and then will be found and put on master's free. Cc: stable@vger.kernel.org # 5.10+ Fixes: 90cd7e424969d ("io_uring: track link timeout's master explicitly") Reported-and-tested-by: syzbot+5a864149dd970b546223@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/69c46bf6ce37fec4fdcd98f0882e18eb07ce693a.1620990121.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index dd8b3fac877c..359d1abb089c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6289,10 +6289,11 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) * We don't expect the list to be empty, that will only happen if we * race with the completion of the linked work. */ - if (prev && req_ref_inc_not_zero(prev)) + if (prev) { io_remove_next_linked(prev); - else - prev = NULL; + if (!req_ref_inc_not_zero(prev)) + prev = NULL; + } spin_unlock_irqrestore(&ctx->completion_lock, flags); if (prev) {