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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 08CFAC2D0E2 for ; Tue, 22 Sep 2020 17:31:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 71C5122206 for ; Tue, 22 Sep 2020 17:31:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="n2rX4xtV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71C5122206 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A45CD900003; Tue, 22 Sep 2020 13:31:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9D042900002; Tue, 22 Sep 2020 13:31:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 89769900003; Tue, 22 Sep 2020 13:31:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0170.hostedemail.com [216.40.44.170]) by kanga.kvack.org (Postfix) with ESMTP id 6BFA6900002 for ; Tue, 22 Sep 2020 13:31:08 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 1BB68181AEF07 for ; Tue, 22 Sep 2020 17:31:08 +0000 (UTC) X-FDA: 77291388216.08.blade30_33100cf2714f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id E94561819E769 for ; Tue, 22 Sep 2020 17:31:07 +0000 (UTC) X-HE-Tag: blade30_33100cf2714f X-Filterd-Recvd-Size: 6152 Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Tue, 22 Sep 2020 17:31:06 +0000 (UTC) Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Tue, 22 Sep 2020 10:30:53 -0700 Received: from rcampbell-dev.nvidia.com (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 22 Sep 2020 17:31:02 +0000 Subject: Re: [PATCH] mm/hmm/test: use after free in dmirror_allocate_chunk() To: Dan Carpenter , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= CC: Jason Gunthorpe , Wei Yongjun , , , References: <20200922081234.GA1274646@mwanda> X-Nvconfidentiality: public From: Ralph Campbell Message-ID: Date: Tue, 22 Sep 2020 10:31:01 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200922081234.GA1274646@mwanda> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1600795853; bh=FlTvSkg2VeAuml+QolVZZc+aE27r29315SlOmjxh39E=; h=Subject:To:CC:References:X-Nvconfidentiality:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=n2rX4xtVEiYQ+FBTCrawg4dcPx1HKTKZZHFu0wsmNM8BaYERwT533PghchwBmk3j8 s5yMw/N9YH0s1iYauljogWzTK3X8jTUXNAPy33WzDSN5K1btEOE4hNX5k53kx58ECM ClVIdF7hiCenQf2kBsArGICJ/IlK45S6P8oh719RJxsPpoYc3+kuLDJnsztru8Ln64 ievHxAsZuu3L1QDQjmjxs4HymhO5JABI6r7NJcW4L6BSXOqBnR3yr6Mk5xaMHZlfls NppkhtfMRJXOM5ZSAZ5JN/3HUGAAf9ZMeXSf1fTzM1YLnmaCiveLzz+YAwb3FK04q+ fpbNBkpGmJlgQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 9/22/20 1:12 AM, Dan Carpenter wrote: > The error handling code does this: > > err_free: > kfree(devmem); > ^^^^^^^^^^^^^ > err_release: > release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range)); > ^^^^^^^^ > The problem is that when we use "devmem->pagemap.range.start" the > "devmem" pointer is either NULL or freed. > > Neither the allocation nor the call to request_free_mem_region() has to > be done under the lock so I moved those to the start of the function. > > Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM") > Signed-off-by: Dan Carpenter > --- > It's weird that I didn't catch the use after free when this code was > merged in May... My bad. Not sure what happened there. How I found > this was that I have been reviewing release_mem_region() leaks and the > NULL dereference path is a leak. > Thanks for fixing this. I missed it too. :-) > lib/test_hmm.c | 47 ++++++++++++++++++++++++----------------------- > 1 file changed, 24 insertions(+), 23 deletions(-) > > diff --git a/lib/test_hmm.c b/lib/test_hmm.c > index c8133f50160b..0503c78cb322 100644 > --- a/lib/test_hmm.c > +++ b/lib/test_hmm.c > @@ -459,6 +459,22 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice, > unsigned long pfn_last; > void *ptr; > > + devmem = kzalloc(sizeof(*devmem), GFP_KERNEL); > + if (!devmem) > + return -ENOMEM; > + > + res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE, > + "hmm_dmirror"); > + if (IS_ERR(res)) > + goto err_devmem; > + > + devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; > + devmem->pagemap.range.start = res->start; > + devmem->pagemap.range.end = res->end; > + devmem->pagemap.nr_range = 1; > + devmem->pagemap.ops = &dmirror_devmem_ops; > + devmem->pagemap.owner = mdevice; > + > mutex_lock(&mdevice->devmem_lock); > > if (mdevice->devmem_count == mdevice->devmem_capacity) { > @@ -471,30 +487,16 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice, > sizeof(new_chunks[0]) * new_capacity, > GFP_KERNEL); > if (!new_chunks) Need to call mutex_unlock(&mdevice->devmem_lock). In fact, why not make this goto err_unlock and add err_unlock: mutex_unlock() before the err_release:. > - goto err; > + goto err_release;> mdevice->devmem_capacity = new_capacity; > mdevice->devmem_chunks = new_chunks; > } > > - res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE, > - "hmm_dmirror"); > - if (IS_ERR(res)) > - goto err; > - > - devmem = kzalloc(sizeof(*devmem), GFP_KERNEL); > - if (!devmem) > - goto err_release; > - > - devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; > - devmem->pagemap.range.start = res->start; > - devmem->pagemap.range.end = res->end; > - devmem->pagemap.nr_range = 1; > - devmem->pagemap.ops = &dmirror_devmem_ops; > - devmem->pagemap.owner = mdevice; > - > ptr = memremap_pages(&devmem->pagemap, numa_node_id()); > - if (IS_ERR(ptr)) > - goto err_free; > + if (IS_ERR(ptr)) { > + mutex_unlock(&mdevice->devmem_lock); > + goto err_release; > + } This could then be just goto err_unlock. > devmem->mdevice = mdevice; > pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT; > @@ -525,12 +527,11 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice, > > return true; > > -err_free: > - kfree(devmem); > err_release: > release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range)); > -err: > - mutex_unlock(&mdevice->devmem_lock); > +err_devmem: > + kfree(devmem); > + > return false; > } > With the suggested change, you can add Reviewed-by: Ralph Campbell