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=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1412DC41604 for ; Tue, 6 Oct 2020 11:57:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 30AB02087E for ; Tue, 6 Oct 2020 11:57:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="lLhpfE52" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 30AB02087E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3303F900002; Tue, 6 Oct 2020 07:57:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2E0196B005D; Tue, 6 Oct 2020 07:57:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 21CE8900002; Tue, 6 Oct 2020 07:57:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0253.hostedemail.com [216.40.44.253]) by kanga.kvack.org (Postfix) with ESMTP id E90CA6B005C for ; Tue, 6 Oct 2020 07:57:06 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 758153634 for ; Tue, 6 Oct 2020 11:57:06 +0000 (UTC) X-FDA: 77341349652.20.coal24_400d1dc271c6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id 5099A180C07AB for ; Tue, 6 Oct 2020 11:57:06 +0000 (UTC) X-HE-Tag: coal24_400d1dc271c6 X-Filterd-Recvd-Size: 5193 Received: from mail-ot1-f66.google.com (mail-ot1-f66.google.com [209.85.210.66]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Tue, 6 Oct 2020 11:57:05 +0000 (UTC) Received: by mail-ot1-f66.google.com with SMTP id q21so11995176ota.8 for ; Tue, 06 Oct 2020 04:57:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0/v0p3FvFQy6vefIiWkN5sABT9yaRl0KmB4aTLtFJ80=; b=lLhpfE52DsBTlXOZaNcfYtajrRM/cDqIwevRSBDcVW4qoPVbzEi7+sihe6YcHp2QOU hnAD2eoXIOk84DvIqJ2RTZpXb49sc13g/2RKsA0kTklQEV+Sykz8QqnvTSECPTErHsRx qsTQaNy+j6UOMtosFQSSws5ErF7y9aC00H4zo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0/v0p3FvFQy6vefIiWkN5sABT9yaRl0KmB4aTLtFJ80=; b=rKt3askLOPRj5I/zya2ySlS9J0u9hVEILAqfQIXd78DJMJUMwQMDfNTUJlNuAOw9+p 1ZcDacQr7NRRQa9IG5HczdtnjunuXYpu2hg3Q+p1ooF2CpQzwC7p19Jo7l0qhsfT/cMu NWcBTC6igtUhVp0xMVViGwbhzrLaEr0ywrUdE/lCL8WEC2eMaW++JzJSM2Y4Hdd26q7D Jk6XhHZ/1AFXNTOTIspZzUgQyMVw85p+yXWvG90XA01bBVZ/fvVHWG/KUrcs4GXmgDOD 5UMXRvrC0Ace5rW87HeG2wmAPOBYNz6kVhorvDtXX7axkEK2Eng/kn1S0ZKj4ilSV2w4 5MKw== X-Gm-Message-State: AOAM53098UOIjDV1Sh/Ua/azn6nPY9h9QUR4BgObhWXj536sglTilKvZ 9DuPc7RsrantP+qD9/dFwp7Nykiz7CO2eHFS6gcOAg== X-Google-Smtp-Source: ABdhPJyMG6+nB6zVd1RDfgIGK4/zu55vJ18yPOXo0KPUU4RdObE/Y3T3eJQEZZwVcpMDmw5VSMtR9OkGz5YHDq9+Jw8= X-Received: by 2002:a05:6830:1c3c:: with SMTP id f28mr2857746ote.188.1601985424516; Tue, 06 Oct 2020 04:57:04 -0700 (PDT) MIME-Version: 1.0 References: <0-v1-447bb60c11dd+174-frame_vec_fix_jgg@nvidia.com> <20201005175308.GI4225@quack2.suse.cz> <20201005175746.GA4734@nvidia.com> In-Reply-To: <20201005175746.GA4734@nvidia.com> From: Daniel Vetter Date: Tue, 6 Oct 2020 13:56:53 +0200 Message-ID: Subject: Re: [PATCH 2/2] mm/frame-vec: use FOLL_LONGTERM To: Jason Gunthorpe Cc: Jan Kara , andrew Morton , Linux MM , Hans Verkuil , Mauro Carvalho Chehab , Mel Gorman , stable , Vlastimil Babka , John Hubbard , DRI Development , LKML , Dan Williams , Linux ARM , linux-samsung-soc , "open list:DMA BUFFER SHARING FRAMEWORK" Content-Type: text/plain; charset="UTF-8" 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 Mon, Oct 5, 2020 at 7:58 PM Jason Gunthorpe wrote: > > On Mon, Oct 05, 2020 at 07:53:08PM +0200, Jan Kara wrote: > > On Mon 05-10-20 14:38:54, Jason Gunthorpe wrote: > > > When get_vaddr_frames() does its hacky follow_pfn() loop it should never > > > be allowed to extract a struct page from a normal VMA. This could allow a > > > serious use-after-free problem on any kernel memory. > > > > > > Restrict this to only work on VMA's with one of VM_IO | VM_PFNMAP > > > set. This limits the use-after-free problem to only IO memory, which while > > > still serious, is an improvement. > > > > > > Cc: stable@vger.kernel.org > > > Fixes: 8025e5ddf9c1 ("[media] mm: Provide new get_vaddr_frames() helper") > > > Signed-off-by: Jason Gunthorpe > > > mm/frame_vector.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > > > index 10f82d5643b6de..26cb20544b6c37 100644 > > > +++ b/mm/frame_vector.c > > > @@ -99,6 +99,10 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > > > if (ret >= nr_frames || start < vma->vm_end) > > > break; > > > vma = find_vma_intersection(mm, start, start + 1); > > > + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { > > > + ret = -EINVAL; > > > + goto out; > > > + } > > > } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP)); > > > > Hum, I fail to see how this helps. If vma has no VM_IO or VM_PFNMAP flag, > > we'd exit the loop (to out: label) anyway due to the loop termination > > condition and why not return the frames we already have? Furthermore > > find_vma_intersection() can return NULL which would oops in your check > > then. What am I missing? > > Oh, nothing, you are right. It just didn't read naturally because > hitting the wrong kind of VMA should be an error condition :\ Also follow_pfn checks for this same conditionat already too, so this isn't really stopping anything bad from happening. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch