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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 51A6BC433C1 for ; Wed, 24 Mar 2021 03:29:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D192C619CA for ; Wed, 24 Mar 2021 03:29:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D192C619CA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3F5D06B0296; Tue, 23 Mar 2021 23:29:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3A5896B029A; Tue, 23 Mar 2021 23:29:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 246306B029C; Tue, 23 Mar 2021 23:29:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0161.hostedemail.com [216.40.44.161]) by kanga.kvack.org (Postfix) with ESMTP id 08A836B0296 for ; Tue, 23 Mar 2021 23:29:49 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id ADEC6814F for ; Wed, 24 Mar 2021 03:29:48 +0000 (UTC) X-FDA: 77953338456.16.993BE70 Received: from m43-7.mailgun.net (m43-7.mailgun.net [69.72.43.7]) by imf27.hostedemail.com (Postfix) with ESMTP id C0E1280192E0 for ; Wed, 24 Mar 2021 03:29:46 +0000 (UTC) DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1616556588; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=00TqvYCNeciOSY+tXTmof3mxA8FUNJGcjvkmvoy4PAM=; b=B/1twW30LJxVM939lNo1ZGmxjCt1zwbHSwPxZqi2zNtsM/iQVRR2Fc6W0qfGOSKhXKN8G7Y8 SD08E5dXIjqy9mUldRQUVRyf+HKpgMd7zp2li8Df1HOGr+szOCFqTZc9Ndx3d6b7Z50glwNd cccTrub7WRJUmSfh2/WUBzJ32D4= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyIwY2Q3OCIsICJsaW51eC1tbUBrdmFjay5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-west-2.postgun.com with SMTP id 605ab22b21031618f63a1836 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 24 Mar 2021 03:29:47 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id E9823C433ED; Wed, 24 Mar 2021 03:29:46 +0000 (UTC) Received: from [192.168.0.109] (unknown [103.110.147.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: vjitta) by smtp.codeaurora.org (Postfix) with ESMTPSA id 4DE6EC433CA; Wed, 24 Mar 2021 03:29:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 4DE6EC433CA 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=fail smtp.mailfrom=vjitta@codeaurora.org Subject: Re: [PATCH] mm: vmalloc: Prevent use after free in _vm_unmap_aliases To: Uladzislau Rezki Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, vinmenon@codeaurora.org References: <1616062105-23263-1-git-send-email-vjitta@codeaurora.org> <20210318165907.GA10448@pc638.lan> From: Vijayanand Jitta Message-ID: <803dc8ec-d1a2-ed26-ddab-a5258e60d318@codeaurora.org> Date: Wed, 24 Mar 2021 08:59:37 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210318165907.GA10448@pc638.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Stat-Signature: gcewmendxgq3rcjxo4z7ubukdqwsnah8 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C0E1280192E0 Received-SPF: none (mg.codeaurora.org>: No applicable sender policy available) receiver=imf27; identity=mailfrom; envelope-from=""; helo=m43-7.mailgun.net; client-ip=69.72.43.7 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616556586-941270 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000017, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/18/2021 10:29 PM, Uladzislau Rezki wrote: > On Thu, Mar 18, 2021 at 03:38:25PM +0530, vjitta@codeaurora.org wrote: >> From: Vijayanand Jitta >> >> A potential use after free can occur in _vm_unmap_aliases >> where an already freed vmap_area could be accessed, Consider >> the following scenario: >> >> Process 1 Process 2 >> >> __vm_unmap_aliases __vm_unmap_aliases >> purge_fragmented_blocks_allcpus rcu_read_lock() >> rcu_read_lock() >> list_del_rcu(&vb->free_list) >> list_for_each_entry_rcu(vb .. ) >> __purge_vmap_area_lazy >> kmem_cache_free(va) >> va_start = vb->va->va_start > Or maybe we should switch to kfree_rcu() instead of kmem_cache_free()? > > -- > Vlad Rezki > Thanks for suggestion. I see free_vmap_area_lock (spinlock) is taken in __purge_vmap_area_lazy while it loops through list and calls kmem_cache_free on va's. So, looks like we can't replace it with kfree_rcu as it might cause scheduling within atomic context. Thanks, Vijay -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation