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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,T_DKIMWL_WL_HIGH, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 4053DC433EF for ; Tue, 12 Jun 2018 17:45:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E76D82086D for ; Tue, 12 Jun 2018 17:45:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="dTUxjHPZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E76D82086D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934193AbeFLRpO (ORCPT ); Tue, 12 Jun 2018 13:45:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:47238 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933574AbeFLRpN (ORCPT ); Tue, 12 Jun 2018 13:45:13 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) (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 4521F20660; Tue, 12 Jun 2018 17:45:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1528825512; bh=X0d/s4r7cZwINA0t1AE4pSdBKw4CfF0hUElmnO6yDl0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dTUxjHPZd5g4a+w9RphsIJ46bVwniLhh3rozVQ0WkoZ7vNXY7jI4NBredeSsLw5s1 SC9BSe0/eulswIaIPWXI/R9cllSdJRaEPfDI0ENXi4Qg7uT4ZslBuomqz2F8zV+6G4 LjFpcMhuBzQbFAH7PxoxTXpDTNKhBPH2/9CgKOZI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro Subject: [PATCH 3.18 07/21] fix io_destroy()/aio_complete() race Date: Tue, 12 Jun 2018 18:52:04 +0200 Message-Id: <20180612164825.712821017@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180612164825.401145490@linuxfoundation.org> References: <20180612164825.401145490@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro commit 4faa99965e027cc057c5145ce45fa772caa04e8d upstream. If io_destroy() gets to cancelling everything that can be cancelled and gets to kiocb_cancel() calling the function driver has left in ->ki_cancel, it becomes vulnerable to a race with IO completion. At that point req is already taken off the list and aio_complete() does *NOT* spin until we (in free_ioctx_users()) releases ->ctx_lock. As the result, it proceeds to kiocb_free(), freing req just it gets passed to ->ki_cancel(). Fix is simple - remove from the list after the call of kiocb_cancel(). All instances of ->ki_cancel() already have to cope with the being called with iocb still on list - that's what happens in io_cancel(2). Cc: stable@kernel.org Fixes: 0460fef2a921 "aio: use cancellation list lazily" Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/aio.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/fs/aio.c +++ b/fs/aio.c @@ -560,9 +560,8 @@ static void free_ioctx_users(struct perc while (!list_empty(&ctx->active_reqs)) { req = list_first_entry(&ctx->active_reqs, struct kiocb, ki_list); - - list_del_init(&req->ki_list); kiocb_cancel(req); + list_del_init(&req->ki_list); } spin_unlock_irq(&ctx->ctx_lock);