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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 2E7EEC2BB55 for ; Thu, 16 Apr 2020 13:45:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D31821734 for ; Thu, 16 Apr 2020 13:45:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587044708; bh=kgB0fWHWLd8OQi91eKRL0HlRnAwZjRg96qiPO2GbR5I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kd5akZn4in3fc4WLUf4m4tCk5yuIyGiJ8oOzdOHPNb29Id3Z+JO1GA2ASfM9IXWCB rO+ORCOFyRpHPdScFpVdACKmWoE1q1Y1wAZBlOHFNu/GUJZHynnpWjyV2VcdvmHl62 GVrS7LjrRVs1bu59ISpk5GnH7doVEu7TC+0zZrP4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2897012AbgDPNpE (ORCPT ); Thu, 16 Apr 2020 09:45:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:45980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2896936AbgDPNe2 (ORCPT ); Thu, 16 Apr 2020 09:34:28 -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 C619E221EB; Thu, 16 Apr 2020 13:34:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587044067; bh=kgB0fWHWLd8OQi91eKRL0HlRnAwZjRg96qiPO2GbR5I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tGCmPzob8xjPKLXvi9pNQSbEG7aCUrCyl4iuIftYXiMr8ZpIAVlVq2Q81WJ5Dvk7l LOBri97tpirlu9FoghGUGB+bRVdBpegCEgK5PIaPDtxLhON215qAJfgm1t/OzlT34K sKwHe54ewi7D0vQo6C2PDAN8Ceok7utuzDbdSoFo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sahitya Tummala , Pradeep P V K , Jens Axboe , Sasha Levin Subject: [PATCH 5.5 066/257] block: Fix use-after-free issue accessing struct io_cq Date: Thu, 16 Apr 2020 15:21:57 +0200 Message-Id: <20200416131334.213420033@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200416131325.891903893@linuxfoundation.org> References: <20200416131325.891903893@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: Sahitya Tummala [ Upstream commit 30a2da7b7e225ef6c87a660419ea04d3cef3f6a7 ] There is a potential race between ioc_release_fn() and ioc_clear_queue() as shown below, due to which below kernel crash is observed. It also can result into use-after-free issue. context#1: context#2: ioc_release_fn() __ioc_clear_queue() gets the same icq ->spin_lock(&ioc->lock); ->spin_lock(&ioc->lock); ->ioc_destroy_icq(icq); ->list_del_init(&icq->q_node); ->call_rcu(&icq->__rcu_head, icq_free_icq_rcu); ->spin_unlock(&ioc->lock); ->ioc_destroy_icq(icq); ->hlist_del_init(&icq->ioc_node); This results into below crash as this memory is now used by icq->__rcu_head in context#1. There is a chance that icq could be free'd as well. 22150.386550: <6> Unable to handle kernel write to read-only memory at virtual address ffffffaa8d31ca50 ... Call trace: 22150.607350: <2> ioc_destroy_icq+0x44/0x110 22150.611202: <2> ioc_clear_queue+0xac/0x148 22150.615056: <2> blk_cleanup_queue+0x11c/0x1a0 22150.619174: <2> __scsi_remove_device+0xdc/0x128 22150.623465: <2> scsi_forget_host+0x2c/0x78 22150.627315: <2> scsi_remove_host+0x7c/0x2a0 22150.631257: <2> usb_stor_disconnect+0x74/0xc8 22150.635371: <2> usb_unbind_interface+0xc8/0x278 22150.639665: <2> device_release_driver_internal+0x198/0x250 22150.644897: <2> device_release_driver+0x24/0x30 22150.649176: <2> bus_remove_device+0xec/0x140 22150.653204: <2> device_del+0x270/0x460 22150.656712: <2> usb_disable_device+0x120/0x390 22150.660918: <2> usb_disconnect+0xf4/0x2e0 22150.664684: <2> hub_event+0xd70/0x17e8 22150.668197: <2> process_one_work+0x210/0x480 22150.672222: <2> worker_thread+0x32c/0x4c8 Fix this by adding a new ICQ_DESTROYED flag in ioc_destroy_icq() to indicate this icq is once marked as destroyed. Also, ensure __ioc_clear_queue() is accessing icq within rcu_read_lock/unlock so that icq doesn't get free'd up while it is still using it. Signed-off-by: Sahitya Tummala Co-developed-by: Pradeep P V K Signed-off-by: Pradeep P V K Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-ioc.c | 7 +++++++ include/linux/iocontext.h | 1 + 2 files changed, 8 insertions(+) diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 5ed59ac6ae58b..9df50fb507caf 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -84,6 +84,7 @@ static void ioc_destroy_icq(struct io_cq *icq) * making it impossible to determine icq_cache. Record it in @icq. */ icq->__rcu_icq_cache = et->icq_cache; + icq->flags |= ICQ_DESTROYED; call_rcu(&icq->__rcu_head, icq_free_icq_rcu); } @@ -212,15 +213,21 @@ static void __ioc_clear_queue(struct list_head *icq_list) { unsigned long flags; + rcu_read_lock(); while (!list_empty(icq_list)) { struct io_cq *icq = list_entry(icq_list->next, struct io_cq, q_node); struct io_context *ioc = icq->ioc; spin_lock_irqsave(&ioc->lock, flags); + if (icq->flags & ICQ_DESTROYED) { + spin_unlock_irqrestore(&ioc->lock, flags); + continue; + } ioc_destroy_icq(icq); spin_unlock_irqrestore(&ioc->lock, flags); } + rcu_read_unlock(); } /** diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index dba15ca8e60bc..1dcd9198beb7f 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -8,6 +8,7 @@ enum { ICQ_EXITED = 1 << 2, + ICQ_DESTROYED = 1 << 3, }; /* -- 2.20.1