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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 64E3DC43381 for ; Thu, 14 Mar 2019 11:33:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F0AE20854 for ; Thu, 14 Mar 2019 11:33:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726612AbfCNLdq (ORCPT ); Thu, 14 Mar 2019 07:33:46 -0400 Received: from mga14.intel.com ([192.55.52.115]:6219 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726501AbfCNLdq (ORCPT ); Thu, 14 Mar 2019 07:33:46 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Mar 2019 04:33:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,478,1544515200"; d="scan'208";a="134010995" Received: from pesmonde-mobl1.ger.corp.intel.com (HELO [10.252.11.115]) ([10.252.11.115]) by orsmga003.jf.intel.com with ESMTP; 14 Mar 2019 04:33:44 -0700 Subject: Re: [Intel-gfx] [PATCH] drm/i915: Sanity check mmap length against object size To: Chris Wilson , intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org References: <20190314075829.16838-1-chris@chris-wilson.co.uk> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc Message-ID: <5572a2bf-1398-04e9-e681-5f7d4e8b9df9@linux.intel.com> Date: Thu, 14 Mar 2019 11:33:43 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190314075829.16838-1-chris@chris-wilson.co.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 14/03/2019 07:58, Chris Wilson wrote: > We assumed that vm_mmap() would reject an attempt to mmap past the end of > the filp (our object), but we were wrong. > > Reported-by: Antonio Argenziano > Testcase: igt/gem_mmap/bad-size > Signed-off-by: Chris Wilson > Cc: Antonio Argenziano > Cc: Joonas Lahtinen > Cc: Tvrtko Ursulin > Cc: stable@vger.kernel.org > --- > drivers/gpu/drm/i915/i915_gem.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index b38c9531b5e8..b7086c8d4726 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1639,8 +1639,13 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data, > * pages from. > */ > if (!obj->base.filp) { > - i915_gem_object_put(obj); > - return -ENXIO; > + addr = -ENXIO; > + goto err; > + } > + > + if (range_overflows(args->offset, args->size, (u64)obj->base.size)) { > + addr = -EINVAL; > + goto err; > } > > addr = vm_mmap(obj->base.filp, 0, args->size, > @@ -1654,8 +1659,8 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data, > struct vm_area_struct *vma; > > if (down_write_killable(&mm->mmap_sem)) { > - i915_gem_object_put(obj); > - return -EINTR; > + addr = -EINTR; > + goto err; > } > vma = find_vma(mm, addr); > if (vma && __vma_matches(vma, obj->base.filp, addr, args->size)) > @@ -1673,12 +1678,10 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data, > i915_gem_object_put(obj); > > args->addr_ptr = (u64)addr; > - > return 0; > > err: > i915_gem_object_put(obj); > - > return addr; > } > > Patch is good, and certainly for our use cases we can afford to check at this level. Reviewed-by: Tvrtko Ursulin I am only wondering what happens to reads/write to the trailing area? Does shmemfs expands the backing store for this mmap and we just end up with otherwise unused chunk at the end? Regards, Tvrtko