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 2C2C0C433DB for ; Wed, 24 Feb 2021 20:06:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ACB0964EC3 for ; Wed, 24 Feb 2021 20:06:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ACB0964EC3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 354898D001D; Wed, 24 Feb 2021 15:06:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2DE516B00E0; Wed, 24 Feb 2021 15:06:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 17E178D001D; Wed, 24 Feb 2021 15:06:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0254.hostedemail.com [216.40.44.254]) by kanga.kvack.org (Postfix) with ESMTP id F0B4E6B00DE for ; Wed, 24 Feb 2021 15:06:56 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id BDA6582C950D for ; Wed, 24 Feb 2021 20:06:56 +0000 (UTC) X-FDA: 77854244832.16.1BA10B6 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf30.hostedemail.com (Postfix) with ESMTP id 3B8C9E00010A for ; Wed, 24 Feb 2021 20:06:56 +0000 (UTC) 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 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 3B8C9E00010A X-Stat-Signature: c4zy8smq1uyphhk95674134mco1uwiph Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf30; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614197216-917458 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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; } _