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[2620:137:e000::1:20]) by mx.google.com with ESMTP id dp14-20020a170906c14e00b007b27afde85csi2118157ejc.707.2022.11.29.07.53.00; Tue, 29 Nov 2022 07:53:24 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=kyY6Gy0J; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236027AbiK2PsE (ORCPT + 99 others); Tue, 29 Nov 2022 10:48:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235775AbiK2Pr6 (ORCPT ); Tue, 29 Nov 2022 10:47:58 -0500 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63FFC5F42 for ; Tue, 29 Nov 2022 07:47:49 -0800 (PST) Received: by mail-wr1-x42a.google.com with SMTP id x17so22742639wrn.6 for ; Tue, 29 Nov 2022 07:47:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=YSdw+42zFeQjk2DGkc/5JCpwWvHgOHoXpertIATsPMg=; b=kyY6Gy0JKC+0AUgiybPvuNjn+SU6DV8iudSjb8b55zB8kB4CqhVidPvZfk6mww3B8n 6tPPi7aTD28MO7gKzrHO+ZFZTkMmX5YCdYvsqIG/OXyXs9ykyLPP5wRNXHSRX0t6RVsh IZX4qH8FwqDWynlcIRmrySVkQJImf/gX52fCnR1vlGWe2x9tFDFP0yt7ZfZIHsBm6j36 kYSmD90/AkP2Qg+2MXUuwV1NFk3p2dA+7dZpdiWsjPuLXQCQpLBU6xTlqxUMgxjOTIMH /nQkV9fl8zI6rpYGdiluQ5g7ciMaMfjc9nt2qlBPLrhiHOj/rqFidysvQv8pXgIoMM3b SNCA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=YSdw+42zFeQjk2DGkc/5JCpwWvHgOHoXpertIATsPMg=; b=O5k9gBUM+S7uiSiqTn1iH78+joylTFyzFVgYr5M6U79Gf7eZei1hNMJ7lJSjpy21+4 SC8tVwOFtt8jw0ZaCst+gQsSVB2ncdL4CnkQy2JenRuxKXihuJ0T07T+ON1evWBbhBw1 abj1MrPKlFtiKqMqsqN0oXG8KnFXAVpzGfZiRuypJjvi/UJleQYJe1J33czTuWhclOus vRN8ml8qdJjoOJzgt0+hzpNwdlhjxu/ixcbxrzrb3g74HzAjVblD9bdKKgk+ROUXHGOt B2ib+vhek+LKobwNSDkVPig5pN7oxcK89z1ZTB9uxcA9DaRgjkFRrweqTIm71R6Q5q7I qsiQ== X-Gm-Message-State: ANoB5pmSr4sRGsHwAF02GxBmVsOZXm5C/VjibwfK7CBVSWsQrC1dnFPU UNnR18EwonFCVFox34pqpg1a7Q== X-Received: by 2002:a5d:5709:0:b0:241:d71c:5dde with SMTP id a9-20020a5d5709000000b00241d71c5ddemr27080262wrv.678.1669736867789; Tue, 29 Nov 2022 07:47:47 -0800 (PST) Received: from localhost ([2a00:79e0:9d:4:5011:adcc:fddd:accf]) by smtp.gmail.com with ESMTPSA id x9-20020a5d6b49000000b002366e3f1497sm14090560wrw.6.2022.11.29.07.47.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Nov 2022 07:47:47 -0800 (PST) From: Jann Horn To: security@kernel.org, Andrew Morton Cc: Yang Shi , David Hildenbrand , Peter Xu , John Hubbard , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v5 3/3] mm/khugepaged: Invoke MMU notifiers in shmem/file collapse paths Date: Tue, 29 Nov 2022 16:47:30 +0100 Message-Id: <20221129154730.2274278-3-jannh@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog In-Reply-To: <20221129154730.2274278-1-jannh@google.com> References: <20221129154730.2274278-1-jannh@google.com> MIME-Version: 1.0 X-Spam-Status: No, score=-17.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1750846358692769437?= X-GMAIL-MSGID: =?utf-8?q?1750846358692769437?= Any codepath that zaps page table entries must invoke MMU notifiers to ensure that secondary MMUs (like KVM) don't keep accessing pages which aren't mapped anymore. Secondary MMUs don't hold their own references to pages that are mirrored over, so failing to notify them can lead to page use-after-free. I'm marking this as addressing an issue introduced in commit f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages"), but most of the security impact of this only came in commit 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP"), which actually omitted flushes for the removal of present PTEs, not just for the removal of empty page tables. Cc: stable@kernel.org Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages") Acked-by: David Hildenbrand Reviewed-by: Yang Shi Signed-off-by: Jann Horn --- Notes: v4: no changes v5: - added ack and reviewed-by mm/khugepaged.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index c3d3ce596bff7..49eb4b4981d88 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1404,6 +1404,7 @@ static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *v unsigned long addr, pmd_t *pmdp) { pmd_t pmd; + struct mmu_notifier_range range; mmap_assert_write_locked(mm); if (vma->vm_file) @@ -1415,8 +1416,12 @@ static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *v if (vma->anon_vma) lockdep_assert_held_write(&vma->anon_vma->root->rwsem); + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, addr, + addr + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); pmd = pmdp_collapse_flush(vma, addr, pmdp); tlb_remove_table_sync_one(); + mmu_notifier_invalidate_range_end(&range); mm_dec_nr_ptes(mm); page_table_check_pte_clear_range(mm, addr, pmd); pte_free(mm, pmd_pgtable(pmd));