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 741E5C4741F for ; Mon, 5 Oct 2020 18:16:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4A65E20B80 for ; Mon, 5 Oct 2020 18:16:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="J0+Lgox+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4A65E20B80 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 B51D4900010; Mon, 5 Oct 2020 14:16:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B02D890000C; Mon, 5 Oct 2020 14:16:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9F0A2900010; Mon, 5 Oct 2020 14:16:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0042.hostedemail.com [216.40.44.42]) by kanga.kvack.org (Postfix) with ESMTP id 6F37A90000C for ; Mon, 5 Oct 2020 14:16:26 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0CD46362D for ; Mon, 5 Oct 2020 18:16:26 +0000 (UTC) X-FDA: 77338676772.07.skirt61_2017e56271c0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id D33411803F9A2 for ; Mon, 5 Oct 2020 18:16:25 +0000 (UTC) X-HE-Tag: skirt61_2017e56271c0 X-Filterd-Recvd-Size: 5378 Received: from mail-ot1-f67.google.com (mail-ot1-f67.google.com [209.85.210.67]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Mon, 5 Oct 2020 18:16:25 +0000 (UTC) Received: by mail-ot1-f67.google.com with SMTP id i12so3729173ota.5 for ; Mon, 05 Oct 2020 11:16:24 -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=o2+egbzisCjaq6nT3TbPZNwblZFYsu8ELcSxPmHmJLs=; b=J0+Lgox+Zl9MR/XcCJjFK6iKg91x1iw1K/lYf26aRsAWa8kYykCWy7QLhvJYCZo/rI 85l/kYnB3V0HE1AMuIcpmFW5+WsQgw3xUFa+j7WIrU1oW0leAypRqp05SrgmM9EUXOaD hCEkIII06FI//qIehI2esTVFpziKPwVbJXmP0= 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=o2+egbzisCjaq6nT3TbPZNwblZFYsu8ELcSxPmHmJLs=; b=Z6WBSbVVIbZY9F+5llbVunwqxb/y1vSsySpVBh1OyU0vumRVUli5DXZr7YU82Fsl/F INUbIK2CgaJyTVZDsbwmOXiavOayHXvqDAMCcJTZAoYyXCwU5qnbfYbyAB25SX0KUQNt 4Ff/2ge/RNOVWl2T7kLmLb0a9yKD26Jnwgd9EPqy/hPls5d5EvKGU7NDS9DkR57n6Fq6 GFU/wMJWljKDE8BOASdbSkHVSs7ehwv1InUR+MLlmT9FfI4WSu4b+WsPHxGhYj9VtOkh 7UwYWDs74iw3UxxEgljtEF3p6Qi4orEGG9dsg5Mv9fan0IMQCVyM7cbMsAdgRxujHVIr WH2Q== X-Gm-Message-State: AOAM530VjL0S5zZmp7OS22XUO8zDTMFaenen2Xe7Iuhf50PtQl5rBhTV yZtOSpWoRbbrSGsRmmwvKeXRvZ5KhdNx0S7jSGRwTQ== X-Google-Smtp-Source: ABdhPJw1WdHFszqHjMyHkkFFS0NFpEwjo9cLd/GAkbhzhWZSM2RoYOtYwo36XdXuPtVVYQY/y+MJINm3GzBdV6PWwoE= X-Received: by 2002:a05:6830:1647:: with SMTP id h7mr392769otr.281.1601921784105; Mon, 05 Oct 2020 11:16:24 -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: Mon, 5 Oct 2020 20:16:12 +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 :\ Afaik these mmio maps should all be VM_DONTEXPAND (or at least the ones in drivers/gpu are all), so not sure why we need the loop here. But maybe there's some drivers that don't set that, or have other funny things going on with userspace piecing the mmap together, and I'm not going to audit them all :-) -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch