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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 DEACCC10F29 for ; Wed, 11 Mar 2020 10:38:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B56E020848 for ; Wed, 11 Mar 2020 10:38:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="NRkbCNZF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728974AbgCKKiG (ORCPT ); Wed, 11 Mar 2020 06:38:06 -0400 Received: from mail26.static.mailgun.info ([104.130.122.26]:49781 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726684AbgCKKiF (ORCPT ); Wed, 11 Mar 2020 06:38:05 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1583923085; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=sybUymT2tahVIh0Sofyvb7j/sJL1ubpg84loPZROPYM=; b=NRkbCNZFdlJLIWCl2JtXkaXCQpuysMPVugEXL9W0DMvDy3ajqx/fK/gXIa7iePnRphgazSm+ XSzV6DSO8ArY2+zv7wcJLbzZlZHL4KsGEKTG9bMkGXGDB3QVJRedlg/dnn8XuMwF5Iz9bJbA c3kScijJi8FaJM06SRpQJ+oyp8k= X-Mailgun-Sending-Ip: 104.130.122.26 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e68bf8b.7fe380132340-smtp-out-n02; Wed, 11 Mar 2020 10:38:03 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 2DE3DC433BA; Wed, 11 Mar 2020 10:38:03 +0000 (UTC) Received: from codeaurora.org (blr-c-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: stummala) by smtp.codeaurora.org (Postfix) with ESMTPSA id 9E3B3C433CB; Wed, 11 Mar 2020 10:38:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 9E3B3C433CB Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=stummala@codeaurora.org From: Sahitya Tummala To: Jens Axboe , linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sahitya Tummala , Pradeep P V K Subject: [PATCH] block: Fix use-after-free issue accessing struct io_cq Date: Wed, 11 Mar 2020 16:07:50 +0530 Message-Id: <1583923070-22245-1-git-send-email-stummala@codeaurora.org> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 5ed59ac..9df50fb 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 dba15ca..1dcd919 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -8,6 +8,7 @@ enum { ICQ_EXITED = 1 << 2, + ICQ_DESTROYED = 1 << 3, }; /* -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.