From patchwork Thu Sep 22 14:10:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liu Shixin X-Patchwork-Id: 12985119 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id F34B3C54EE9 for ; Thu, 22 Sep 2022 13:36:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 81D9580009; Thu, 22 Sep 2022 09:36:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7CD9380007; Thu, 22 Sep 2022 09:36:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 695CA80009; Thu, 22 Sep 2022 09:36:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 5A50F80007 for ; Thu, 22 Sep 2022 09:36:24 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 292811405EA for ; Thu, 22 Sep 2022 13:36:24 +0000 (UTC) X-FDA: 79939820688.30.4603B21 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by imf26.hostedemail.com (Postfix) with ESMTP id 2837C140027 for ; Thu, 22 Sep 2022 13:36:22 +0000 (UTC) Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4MYGTY3MjDzHqKX; Thu, 22 Sep 2022 21:34:09 +0800 (CST) Received: from dggpemm100009.china.huawei.com (7.185.36.113) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 22 Sep 2022 21:36:18 +0800 Received: from huawei.com (10.175.113.32) by dggpemm100009.china.huawei.com (7.185.36.113) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 22 Sep 2022 21:36:19 +0800 From: Liu Shixin To: Liu Zixian , Mike Kravetz , Muchun Song , "Andrew Morton" , Sidhartha Kumar , John Hubbard , "David Hildenbrand" , Kefeng Wang CC: , , Liu Shixin Subject: [PATCH v2] mm: hugetlb: fix UAF in hugetlb_handle_userfault Date: Thu, 22 Sep 2022 22:10:02 +0800 Message-ID: <20220922141002.3242443-1-liushixin2@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.113.32] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm100009.china.huawei.com (7.185.36.113) X-CFilter-Loop: Reflected ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=none; spf=pass (imf26.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=liushixin2@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663853783; a=rsa-sha256; cv=none; b=NYT1eSyaD6pxcqZXhgyCtzdZieMpjWhvOOz25yCHNJmEJ849VPBUX+2TnGBaPvA7aCQAsR ZH+goBm5gQ/wlr6FYjScyjBm0h5rSvyzH8F9SKkjObp19gleS5i6UAW88eNb0oXV89A+YC oTlepRUd+I8qBTF8Huk//v6DMTd2s2w= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663853783; h=from:from:sender: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: references; bh=ddtBDpMU8tPb7mVcTQy52WmNij01bkXyV8E/v4shLc0=; b=7FO6BtMqhjkzUHFUzOkzy1wg1uYxWxvTDZ40zgfXY/2HQxZYBaaFXOXEkhDq9bHhbyUuu3 65Xlb0SjZfEcGlltqZ5cpUePV7nqQXFikE5dwaXCJPRkTOFhbFVKtnjLdP5SzsjPKsBLav omg7uYubT0EG8melI3qwDsGPcpG+uuY= Authentication-Results: imf26.hostedemail.com; dkim=none; spf=pass (imf26.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=liushixin2@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspamd-Server: rspam06 X-Stat-Signature: kq8kctpfdx1hygeikioy7c9wd1x7ox16 X-Rspam-User: X-Rspamd-Queue-Id: 2837C140027 X-HE-Tag: 1663853782-981146 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: The vma_lock and hugetlb_fault_mutex are dropped before handling userfault and reacquire them again after handle_userfault(), but reacquire the vma_lock could lead to UAF[1,2] due to the following race, hugetlb_fault hugetlb_no_page /*unlock vma_lock */ hugetlb_handle_userfault handle_userfault /* unlock mm->mmap_lock*/ vm_mmap_pgoff do_mmap mmap_region munmap_vma_range /* clean old vma */ /* lock vma_lock again <--- UAF */ /* unlock vma_lock */ Since the vma_lock will unlock immediately after hugetlb_handle_userfault(), let's drop the unneeded lock and unlock in hugetlb_handle_userfault() to fix the issue. [1] https://lore.kernel.org/linux-mm/000000000000d5e00a05e834962e@google.com/ [2] https://lore.kernel.org/linux-mm/20220921014457.1668-1-liuzixian4@huawei.com/ Reported-by: syzbot+193f9cee8638750b23cf@syzkaller.appspotmail.com Reported-by: Liu Zixian Fixes: 1a1aad8a9b7b ("userfaultfd: hugetlbfs: add userfaultfd hugetlb hook") CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Liu Shixin Signed-off-by: Kefeng Wang Reviewed-by: Mike Kravetz --- mm/hugetlb.c | 30 +++++++++++------------------- 1 file changed, 11 insertions(+), 19 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 9b8526d27c29..5a5d466692cf 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5489,7 +5489,6 @@ static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma, unsigned long addr, unsigned long reason) { - vm_fault_t ret; u32 hash; struct vm_fault vmf = { .vma = vma, @@ -5508,17 +5507,12 @@ static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma, /* * vma_lock and hugetlb_fault_mutex must be - * dropped before handling userfault. Reacquire - * after handling fault to make calling code simpler. + * dropped before handling userfault. */ hugetlb_vma_unlock_read(vma); hash = hugetlb_fault_mutex_hash(mapping, idx); mutex_unlock(&hugetlb_fault_mutex_table[hash]); - ret = handle_userfault(&vmf, reason); - mutex_lock(&hugetlb_fault_mutex_table[hash]); - hugetlb_vma_lock_read(vma); - - return ret; + return handle_userfault(&vmf, reason); } static vm_fault_t hugetlb_no_page(struct mm_struct *mm, @@ -5537,6 +5531,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, unsigned long haddr = address & huge_page_mask(h); bool new_page, new_pagecache_page = false; bool reserve_alloc = false; + u32 hash = hugetlb_fault_mutex_hash(mapping, idx); /* * Currently, we are forced to kill the process in the event the @@ -5547,7 +5542,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n", current->pid); - return ret; + goto out; } /* @@ -5561,12 +5556,10 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, if (idx >= size) goto out; /* Check for page in userfault range */ - if (userfaultfd_missing(vma)) { - ret = hugetlb_handle_userfault(vma, mapping, idx, + if (userfaultfd_missing(vma)) + return hugetlb_handle_userfault(vma, mapping, idx, flags, haddr, address, VM_UFFD_MISSING); - goto out; - } page = alloc_huge_page(vma, haddr, 0); if (IS_ERR(page)) { @@ -5634,10 +5627,9 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, if (userfaultfd_minor(vma)) { unlock_page(page); put_page(page); - ret = hugetlb_handle_userfault(vma, mapping, idx, + return hugetlb_handle_userfault(vma, mapping, idx, flags, haddr, address, VM_UFFD_MINOR); - goto out; } } @@ -5695,6 +5687,8 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, unlock_page(page); out: + hugetlb_vma_unlock_read(vma); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); return ret; backout: @@ -5792,11 +5786,9 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, entry = huge_ptep_get(ptep); /* PTE markers should be handled the same way as none pte */ - if (huge_pte_none_mostly(entry)) { - ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, + if (huge_pte_none_mostly(entry)) + return hugetlb_no_page(mm, vma, mapping, idx, address, ptep, entry, flags); - goto out_mutex; - } ret = 0;