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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 EA21DC433E9 for ; Wed, 24 Feb 2021 20:06:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B37E364F25 for ; Wed, 24 Feb 2021 20:06:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235270AbhBXUGi (ORCPT ); Wed, 24 Feb 2021 15:06:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:56272 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234718AbhBXUFy (ORCPT ); Wed, 24 Feb 2021 15:05:54 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7A1D164F29; Wed, 24 Feb 2021 20:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614197083; bh=AkQdFROiB4kD2nW5q7VH4tUqdd3BV6k+AP0uR4ayswc=; h=Date:From:To:Subject:In-Reply-To:From; b=e9XDXRGhwP0WHk4ljHoV9sgAL1d2A9TvarTG13j1TYLoItgmwP50tMTRsdD7dPFwz 0g68dzJRBvX+iBTeOjS4tEIqW5rFT5YdvDhCxEdOkVE28KFzNb5g/JQvOeOkieTSKP Rn3xyBqUPXSrIO0o/XOfUCkQQW8IJNRaUtOF4wKI= Date: Wed, 24 Feb 2021 12:04:42 -0800 From: Andrew Morton To: akpm@linux-foundation.org, chrisw@sous-sol.org, ian.pratt@xensource.com, linmiaohe@huawei.com, linux-mm@kvack.org, mingo@elte.hu, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 080/173] mm/memory.c: fix potential pte_unmap_unlock pte error Message-ID: <20210224200442.Apg5eElaa%akpm@linux-foundation.org> In-Reply-To: <20210224115824.1e289a6895087f10c41dd8d6@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Miaohe Lin Subject: mm/memory.c: fix potential pte_unmap_unlock pte error 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. Link: https://lkml.kernel.org/r/20210205081925.59809-1-linmiaohe@huawei.com Fixes: aee16b3cee27 ("Add apply_to_page_range() which applies a function to a pte range") Signed-off-by: Miaohe Lin Reviewed-by: Andrew Morton Cc: Ingo Molnar Cc: Ian Pratt Cc: Chris Wright Signed-off-by: Andrew Morton --- mm/memory.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/mm/memory.c~mm-memoryc-fix-potential-pte_unmap_unlock-pte-error +++ a/mm/memory.c @@ -2394,18 +2394,18 @@ static int apply_to_pte_range(struct mm_ 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_ arch_leave_lazy_mmu_mode(); if (mm != &init_mm) - pte_unmap_unlock(pte-1, ptl); + pte_unmap_unlock(mapped_pte, ptl); return err; } _