From patchwork Mon Mar 1 16:13:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 390247 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 91130C4332D for ; Mon, 1 Mar 2021 16:30:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5141564F4D for ; Mon, 1 Mar 2021 16:30:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234676AbhCAQ2l (ORCPT ); Mon, 1 Mar 2021 11:28:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:59986 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235234AbhCAQXs (ORCPT ); Mon, 1 Mar 2021 11:23:48 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 410E364F29; Mon, 1 Mar 2021 16:20:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614615603; bh=oDpCdDtQKZMbgugknVR9spXcuzm05hoc07BkVvCUtj0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lR52bkAi9h01eFYB5EbGQnnervnhN3ggFjSRilackoUpIjwusJnqd7nUM+YdtF7Xd 5ymx0qPSmApp4UOlHraEIpx1D3bd0MHHoy1bq5z6XS8uAdoCvoEhiw6p+PvjJL1iYl 9nY3CSRLCy7DUTQTDjm3iFARIup7PGYYZD/DtdUE= 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 4.4 58/93] mm/memory.c: fix potential pte_unmap_unlock pte error Date: Mon, 1 Mar 2021 17:13:10 +0100 Message-Id: <20210301161009.740412714@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161006.881950696@linuxfoundation.org> References: <20210301161006.881950696@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 fa752df6dc857..86ca97c24f1d9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1686,11 +1686,11 @@ 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(); @@ -1704,7 +1704,7 @@ 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; }