From patchwork Mon Mar 1 16:13:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 390010 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=-18.8 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 08293C433E0 for ; Mon, 1 Mar 2021 17:19:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5D1C651EE for ; Mon, 1 Mar 2021 17:19:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237843AbhCARTM (ORCPT ); Mon, 1 Mar 2021 12:19:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:50362 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237048AbhCARM0 (ORCPT ); Mon, 1 Mar 2021 12:12:26 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1AAB765024; Mon, 1 Mar 2021 16:43:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614617009; bh=geWY4EmGmVM6Oxl40KIOniYuhR6bQjVCTp6XaDRTJ70=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FBlSGHpUjtj1uEzK3FlvGyeeAodD/vDdAMeEY3Ah77U/G8Ik2Jq3nwJshlxbE4Rgx wxxoHXhXXxDaN34cOG/Auwv1KRI3tTTabf9Yv6dKQXWKGMZi7sBPLw0FpnWrcUW+Zy Fe4+MacEEaWGkodwM3uExYtH94AusqQhH97fNzyo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hongxiang Lou , Miaohe Lin , Thomas Gleixner , Dave Hansen , Andi Kleen , Josh Poimboeuf , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 171/247] mm/memory.c: fix potential pte_unmap_unlock pte error Date: Mon, 1 Mar 2021 17:13:11 +0100 Message-Id: <20210301161040.032948334@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161031.684018251@linuxfoundation.org> References: <20210301161031.684018251@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Miaohe Lin [ Upstream commit 90a3e375d324b2255b83e3dd29e99e2b05d82aaf ] Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed, we would break the loop with pte unchanged. Then the wrong pte - 1 would be passed to pte_unmap_unlock. Andi said: "While the fix is correct, I'm not sure if it actually is a real bug. Is there any architecture that would do something else than unlocking the underlying page? If it's just the underlying page then it should be always the same page, so no bug" Link: https://lkml.kernel.org/r/20210109080118.20885-1-linmiaohe@huawei.com Fixes: 42e4089c789 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings") Signed-off-by: Hongxiang Lou Signed-off-by: Miaohe Lin Cc: Thomas Gleixner Cc: Dave Hansen Cc: Andi Kleen Cc: Josh Poimboeuf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/memory.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index eeae63bd95027..4bd37296df89b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1995,11 +1995,11 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, unsigned long addr, unsigned long end, unsigned long pfn, pgprot_t prot) { - pte_t *pte; + pte_t *pte, *mapped_pte; spinlock_t *ptl; int err = 0; - pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); + mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); if (!pte) return -ENOMEM; arch_enter_lazy_mmu_mode(); @@ -2013,7 +2013,7 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, pfn++; } while (pte++, addr += PAGE_SIZE, addr != end); arch_leave_lazy_mmu_mode(); - pte_unmap_unlock(pte - 1, ptl); + pte_unmap_unlock(mapped_pte, ptl); return err; }