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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,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 27867C67839 for ; Fri, 14 Dec 2018 12:17:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE9642148E for ; Fri, 14 Dec 2018 12:17:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544789828; bh=kGPn44POXcr1cm6LnGg8xi5OesJ0PYxwW7NQVuioPfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gmyJ3gTQz3Oy+/dlSE1U2ZpCmL5WZc6XHtL4GgUy7aq5bni/i3ucEZd9dpniPEzP0 4iMl1nPew80OVyPhQG7GB88w38bVhyy8yEHbZZHIcKmrJqIRSbBJ7AL3cI2Ti7Vh2n ZcEu3t0WfUCvVg7y+h2MWWE0SJdiT5muU0uq23uw= DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE9642148E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732879AbeLNMRG (ORCPT ); Fri, 14 Dec 2018 07:17:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:37318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732864AbeLNMRD (ORCPT ); Fri, 14 Dec 2018 07:17:03 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 84AC1214F1; Fri, 14 Dec 2018 12:17:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544789822; bh=kGPn44POXcr1cm6LnGg8xi5OesJ0PYxwW7NQVuioPfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PHYzyY5m+DjRR8fPe8SRo5RK9GHf5dgRHkEK0F4RuHDWAuxZIUnkgia+YVYpNidcz LugqaKSAKKQuu0lTWBVL/EFhk51NxltNLUvl2AD++R4kpwD2FLoKCvyxgOq8JjOuuf hdQfAM+LzFdJpVPQV6jYngvQY2+9Q4QOH5uNWQWc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Ben Hutchings Subject: [PATCH 4.4 82/88] proc: dont use FOLL_FORCE for reading cmdline and environment Date: Fri, 14 Dec 2018 13:00:56 +0100 Message-Id: <20181214115708.851388434@linuxfoundation.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20181214115702.151309521@linuxfoundation.org> References: <20181214115702.151309521@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Linus Torvalds commit 272ddc8b37354c3fe111ab26d25e792629148eee upstream. Now that Lorenzo cleaned things up and made the FOLL_FORCE users explicit, it becomes obvious how some of them don't really need FOLL_FORCE at all. So remove FOLL_FORCE from the proc code that reads the command line and arguments from user space. The mem_rw() function actually does want FOLL_FORCE, because gdd (and possibly many other debuggers) use it as a much more convenient version of PTRACE_PEEKDATA, but we should consider making the FOLL_FORCE part conditional on actually being a ptracer. This does not actually do that, just moves adds a comment to that effect and moves the gup_flags settings next to each other. Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- fs/proc/base.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -254,7 +254,7 @@ static ssize_t proc_pid_cmdline_read(str * Inherently racy -- command line shares address space * with code and data. */ - rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_FORCE); + rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0); if (rv <= 0) goto out_free_page; @@ -272,8 +272,7 @@ static ssize_t proc_pid_cmdline_read(str int nr_read; _count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, - FOLL_FORCE); + nr_read = access_remote_vm(mm, p, page, _count, 0); if (nr_read < 0) rv = nr_read; if (nr_read <= 0) @@ -308,8 +307,7 @@ static ssize_t proc_pid_cmdline_read(str bool final; _count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, - FOLL_FORCE); + nr_read = access_remote_vm(mm, p, page, _count, 0); if (nr_read < 0) rv = nr_read; if (nr_read <= 0) @@ -358,8 +356,7 @@ skip_argv: bool final; _count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, - FOLL_FORCE); + nr_read = access_remote_vm(mm, p, page, _count, 0); if (nr_read < 0) rv = nr_read; if (nr_read <= 0) @@ -871,7 +868,7 @@ static ssize_t mem_rw(struct file *file, unsigned long addr = *ppos; ssize_t copied; char *page; - unsigned int flags = FOLL_FORCE; + unsigned int flags; if (!mm) return 0; @@ -884,6 +881,8 @@ static ssize_t mem_rw(struct file *file, if (!atomic_inc_not_zero(&mm->mm_users)) goto free; + /* Maybe we should limit FOLL_FORCE to actual ptrace users? */ + flags = FOLL_FORCE; if (write) flags |= FOLL_WRITE; @@ -1007,8 +1006,7 @@ static ssize_t environ_read(struct file max_len = min_t(size_t, PAGE_SIZE, count); this_len = min(max_len, this_len); - retval = access_remote_vm(mm, (env_start + src), - page, this_len, FOLL_FORCE); + retval = access_remote_vm(mm, (env_start + src), page, this_len, 0); if (retval <= 0) { ret = retval;