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=-20.8 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,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 781B8C433EF for ; Wed, 8 Sep 2021 19:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 570586113C for ; Wed, 8 Sep 2021 19:03:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241581AbhIHTEX (ORCPT ); Wed, 8 Sep 2021 15:04:23 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:54086 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230044AbhIHTEW (ORCPT ); Wed, 8 Sep 2021 15:04:22 -0400 Date: Wed, 08 Sep 2021 19:03:11 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1631127793; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Cc4XKzlAxS2JV3J1f8eqsKquDD1+Lo6QrqMckR6OU9E=; b=2a9isP1SrMzoKsMARCnOodf/AOZ4OZtCWOdXAC1t+/rWl6OvwXl26r4/KFYZKnaTiuoXd9 xAuzMdfiZ07CKIdOTJEUycBlhcEaZwEk75weluEC6m5wChahDeuET4euXuTs5oFYUHLZcz PZDqbxYdnZksqK3LRVoFN1E6KZOaQWssSlPEHyV8Z9hFMuFfubt19RQbrdPsEhvfS6OUs8 ccmI+bOH62lRUEsew9wkjEgF0B6EcrQYr33hhTtKolWH11TsLeuxfxVeTLsATdyGMm3kgo HXE1dc3/XLsQsf7kMVol79UmncR5IshfRbeCy5kR9F54SGlXifz1Bpt8ImVIlw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1631127793; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Cc4XKzlAxS2JV3J1f8eqsKquDD1+Lo6QrqMckR6OU9E=; b=mrTXsTWCaeOhZ6ev+EEwpnC9sR5WC5nHWYBli36E25xcC8vdjA2gJGqbebGKjmju251SWJ obpS3wTu0wVfmrCg== From: "tip-bot2 for Mike Rapoport" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/mm: Fix kern_addr_valid() to cope with existing but not present entries Cc: Jiri Olsa , Mike Rapoport , Borislav Petkov , David Hildenbrand , Dave Hansen , , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210819132717.19358-1-rppt@kernel.org> References: <20210819132717.19358-1-rppt@kernel.org> MIME-Version: 1.0 Message-ID: <163112779151.25758.9291514239160548248.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 34b1999da935a33be6239226bfa6cd4f704c5c88 Gitweb: https://git.kernel.org/tip/34b1999da935a33be6239226bfa6cd4f704c5c88 Author: Mike Rapoport AuthorDate: Thu, 19 Aug 2021 16:27:17 +03:00 Committer: Borislav Petkov CommitterDate: Wed, 08 Sep 2021 20:50:32 +02:00 x86/mm: Fix kern_addr_valid() to cope with existing but not present entries Jiri Olsa reported a fault when running: # cat /proc/kallsyms | grep ksys_read ffffffff8136d580 T ksys_read # objdump -d --start-address=0xffffffff8136d580 --stop-address=0xffffffff8136d590 /proc/kcore /proc/kcore: file format elf64-x86-64 Segmentation fault general protection fault, probably for non-canonical address 0xf887ffcbff000: 0000 [#1] SMP PTI CPU: 12 PID: 1079 Comm: objdump Not tainted 5.14.0-rc5qemu+ #508 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-4.fc34 04/01/2014 RIP: 0010:kern_addr_valid Call Trace: read_kcore ? rcu_read_lock_sched_held ? rcu_read_lock_sched_held ? rcu_read_lock_sched_held ? trace_hardirqs_on ? rcu_read_lock_sched_held ? lock_acquire ? lock_acquire ? rcu_read_lock_sched_held ? lock_acquire ? rcu_read_lock_sched_held ? rcu_read_lock_sched_held ? rcu_read_lock_sched_held ? lock_release ? _raw_spin_unlock ? __handle_mm_fault ? rcu_read_lock_sched_held ? lock_acquire ? rcu_read_lock_sched_held ? lock_release proc_reg_read ? vfs_read vfs_read ksys_read do_syscall_64 entry_SYSCALL_64_after_hwframe The fault happens because kern_addr_valid() dereferences existent but not present PMD in the high kernel mappings. Such PMDs are created when free_kernel_image_pages() frees regions larger than 2Mb. In this case, a part of the freed memory is mapped with PMDs and the set_memory_np_noalias() -> ... -> __change_page_attr() sequence will mark the PMD as not present rather than wipe it completely. Have kern_addr_valid() check whether higher level page table entries are present before trying to dereference them to fix this issue and to avoid similar issues in the future. Stable backporting note: ------------------------ Note that the stable marking is for all active stable branches because there could be cases where pagetable entries exist but are not valid - see 9a14aefc1d28 ("x86: cpa, fix lookup_address"), for example. So make sure to be on the safe side here and use pXY_present() accessors rather than pXY_none() which could #GP when accessing pages in the direct map. Also see: c40a56a7818c ("x86/mm/init: Remove freed kernel image areas from alias mapping") for more info. Reported-by: Jiri Olsa Signed-off-by: Mike Rapoport Signed-off-by: Borislav Petkov Reviewed-by: David Hildenbrand Acked-by: Dave Hansen Tested-by: Jiri Olsa Cc: # 4.4+ Link: https://lkml.kernel.org/r/20210819132717.19358-1-rppt@kernel.org --- arch/x86/mm/init_64.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index ddeaba9..879886c 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1433,18 +1433,18 @@ int kern_addr_valid(unsigned long addr) return 0; p4d = p4d_offset(pgd, addr); - if (p4d_none(*p4d)) + if (!p4d_present(*p4d)) return 0; pud = pud_offset(p4d, addr); - if (pud_none(*pud)) + if (!pud_present(*pud)) return 0; if (pud_large(*pud)) return pfn_valid(pud_pfn(*pud)); pmd = pmd_offset(pud, addr); - if (pmd_none(*pmd)) + if (!pmd_present(*pmd)) return 0; if (pmd_large(*pmd))