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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 8452AC433DB for ; Fri, 5 Feb 2021 08:20:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30EAF64F9E for ; Fri, 5 Feb 2021 08:20:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231640AbhBEIU4 (ORCPT ); Fri, 5 Feb 2021 03:20:56 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:12130 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231253AbhBEIUw (ORCPT ); Fri, 5 Feb 2021 03:20:52 -0500 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4DX7bp2JsFz164kW; Fri, 5 Feb 2021 16:18:46 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.498.0; Fri, 5 Feb 2021 16:19:58 +0800 From: Miaohe Lin To: CC: , , , , , , Subject: [PATCH] mm/memory.c: fix potential pte_unmap_unlock pte error Date: Fri, 5 Feb 2021 03:19:25 -0500 Message-ID: <20210205081925.59809-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If all pte entry is none in 'non-create' case, we would break the loop with pte unchanged. Then the wrong pte - 1 would be passed to pte_unmap_unlock. This is a theoretical issue which may not be a real bug. So it's not worth cc stable. Fixes: aee16b3cee27 ("Add apply_to_page_range() which applies a function to a pte range") Signed-off-by: Miaohe Lin --- mm/memory.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 9d68a2340589..b2d6a0a6088b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2394,18 +2394,18 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, pte_fn_t fn, void *data, bool create, pgtbl_mod_mask *mask) { - pte_t *pte; + pte_t *pte, *mapped_pte; int err = 0; spinlock_t *ptl; if (create) { - pte = (mm == &init_mm) ? + mapped_pte = pte = (mm == &init_mm) ? pte_alloc_kernel_track(pmd, addr, mask) : pte_alloc_map_lock(mm, pmd, addr, &ptl); if (!pte) return -ENOMEM; } else { - pte = (mm == &init_mm) ? + mapped_pte = pte = (mm == &init_mm) ? pte_offset_kernel(pmd, addr) : pte_offset_map_lock(mm, pmd, addr, &ptl); } @@ -2428,7 +2428,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, arch_leave_lazy_mmu_mode(); if (mm != &init_mm) - pte_unmap_unlock(pte-1, ptl); + pte_unmap_unlock(mapped_pte, ptl); return err; } -- 2.19.1