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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 F145FC2D0DB for ; Tue, 28 Jan 2020 14:06:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C3D8124681 for ; Tue, 28 Jan 2020 14:06:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580220418; bh=tKyRT6zwCMjcUPxdZNGLWuSNWGv/b1e6eBAIZMS8VkI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eigRNTXJlPktV8etQciQJ9dVkvvWk+dLNt9WpU+5SF1Fnk1ysCokefcSmBQYcZGpi AROR7HDOh8tBb+AZ/EYqclIfscHvYoboLp54ChRx0GiXKN6ujSEFkduv4lcVWzMfsZ PWzGtamQJx9M9r5b1hPevgAtTlGtkBZxJcA2WWAw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727427AbgA1OEA (ORCPT ); Tue, 28 Jan 2020 09:04:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:50934 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727266AbgA1OEA (ORCPT ); Tue, 28 Jan 2020 09:04:00 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 02FAA24685; Tue, 28 Jan 2020 14:03:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580220239; bh=tKyRT6zwCMjcUPxdZNGLWuSNWGv/b1e6eBAIZMS8VkI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JE56JGkhb/XVk75ZTHZNkAb4Bq95mo4Wc0/QxSOHx2XkqCsW4qB5+hoG/fYOQOvhA S98/MDb9da5lN4cmHt1kMzyA2elNC8Lp1RpFxSjXyFmWL6nolr75/G97fCdSIDgEK7 hgPo7d3vaMPQl8WTU+C7m+KbZReP/sNhNCIelkzA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christophe Leroy , Linus Torvalds Subject: [PATCH 5.4 071/104] lib: Reduce user_access_begin() boundaries in strncpy_from_user() and strnlen_user() Date: Tue, 28 Jan 2020 15:00:32 +0100 Message-Id: <20200128135827.156445118@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200128135817.238524998@linuxfoundation.org> References: <20200128135817.238524998@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Christophe Leroy commit ab10ae1c3bef56c29bac61e1201c752221b87b41 upstream. The range passed to user_access_begin() by strncpy_from_user() and strnlen_user() starts at 'src' and goes up to the limit of userspace although reads will be limited by the 'count' param. On 32 bits powerpc (book3s/32) access has to be granted for each 256Mbytes segment and the cost increases with the number of segments to unlock. Limit the range with 'count' param. Fixes: 594cc251fdd0 ("make 'user_access_begin()' do 'access_ok()'") Signed-off-by: Christophe Leroy Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- lib/strncpy_from_user.c | 14 +++++++------- lib/strnlen_user.c | 14 +++++++------- 2 files changed, 14 insertions(+), 14 deletions(-) --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -30,13 +30,6 @@ static inline long do_strncpy_from_user( const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; unsigned long res = 0; - /* - * Truncate 'max' to the user-specified limit, so that - * we only have one limit we need to check in the loop - */ - if (max > count) - max = count; - if (IS_UNALIGNED(src, dst)) goto byte_at_a_time; @@ -114,6 +107,13 @@ long strncpy_from_user(char *dst, const unsigned long max = max_addr - src_addr; long retval; + /* + * Truncate 'max' to the user-specified limit, so that + * we only have one limit we need to check in the loop + */ + if (max > count) + max = count; + kasan_check_write(dst, count); check_object_size(dst, count, false); if (user_access_begin(src, max)) { --- a/lib/strnlen_user.c +++ b/lib/strnlen_user.c @@ -27,13 +27,6 @@ static inline long do_strnlen_user(const unsigned long c; /* - * Truncate 'max' to the user-specified limit, so that - * we only have one limit we need to check in the loop - */ - if (max > count) - max = count; - - /* * Do everything aligned. But that means that we * need to also expand the maximum.. */ @@ -109,6 +102,13 @@ long strnlen_user(const char __user *str unsigned long max = max_addr - src_addr; long retval; + /* + * Truncate 'max' to the user-specified limit, so that + * we only have one limit we need to check in the loop + */ + if (max > count) + max = count; + if (user_access_begin(str, max)) { retval = do_strnlen_user(str, count, max); user_access_end();