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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 03096C28E86 for ; Mon, 15 Mar 2021 13:59:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBB6764F2E for ; Mon, 15 Mar 2021 13:59:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232260AbhCON6q (ORCPT ); Mon, 15 Mar 2021 09:58:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:36728 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232071AbhCON6J (ORCPT ); Mon, 15 Mar 2021 09:58:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C9A9C64F38; Mon, 15 Mar 2021 13:58:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615816689; bh=s0igxtKMfYxA8SVvVJiw7ZJu0AVVuctGKDjev/kC1WE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NzMPgJ3KjK5rRQUIqRfT0zj1kfF8ClOBYHC4UG86/hLVPcACQxNv8qeOxDAj1QREU MFONFfn9V+HwrIBJufYP2xjNlhnBno0Cx8ieQjr1vok3J0IhDN5ltdeV/yVIcM2suT o217AmVfmMaKs/7ct2oNXkyhXq8QFKd36W4ebZ1w= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neil Roberts , Steven Price , Maarten Lankhorst Subject: [PATCH 5.4 048/168] drm/shmem-helper: Check for purged buffers in fault handler Date: Mon, 15 Mar 2021 14:54:40 +0100 Message-Id: <20210315135551.941962641@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135550.333963635@linuxfoundation.org> References: <20210315135550.333963635@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Greg Kroah-Hartman From: Neil Roberts commit d611b4a0907cece060699f2fd347c492451cd2aa upstream. When a buffer is madvised as not needed and then purged, any attempts to access the buffer from user-space should cause a bus fault. This patch adds a check for that. Cc: stable@vger.kernel.org Fixes: 17acb9f35ed7 ("drm/shmem: Add madvise state and purge helpers") Signed-off-by: Neil Roberts Reviewed-by: Steven Price Signed-off-by: Steven Price Link: https://patchwork.freedesktop.org/patch/msgid/20210223155125.199577-2-nroberts@igalia.com Signed-off-by: Maarten Lankhorst Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_gem_shmem_helper.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -474,14 +474,24 @@ static vm_fault_t drm_gem_shmem_fault(st struct drm_gem_object *obj = vma->vm_private_data; struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); loff_t num_pages = obj->size >> PAGE_SHIFT; + vm_fault_t ret; struct page *page; - if (vmf->pgoff >= num_pages || WARN_ON_ONCE(!shmem->pages)) - return VM_FAULT_SIGBUS; + mutex_lock(&shmem->pages_lock); - page = shmem->pages[vmf->pgoff]; + if (vmf->pgoff >= num_pages || + WARN_ON_ONCE(!shmem->pages) || + shmem->madv < 0) { + ret = VM_FAULT_SIGBUS; + } else { + page = shmem->pages[vmf->pgoff]; - return vmf_insert_page(vma, vmf->address, page); + ret = vmf_insert_page(vma, vmf->address, page); + } + + mutex_unlock(&shmem->pages_lock); + + return ret; } static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)