From patchwork Wed Sep 21 08:34:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liu Shixin X-Patchwork-Id: 12983330 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 BD378C32771 for ; Wed, 21 Sep 2022 08:01:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0C93B6B0072; Wed, 21 Sep 2022 04:01:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 079EB6B0073; Wed, 21 Sep 2022 04:01:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E850E6B0074; Wed, 21 Sep 2022 04:01:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id DA3916B0072 for ; Wed, 21 Sep 2022 04:01:03 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 8C836802B8 for ; Wed, 21 Sep 2022 08:01:03 +0000 (UTC) X-FDA: 79935346806.22.F47BCDD Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf15.hostedemail.com (Postfix) with ESMTP id 9D409A0006 for ; Wed, 21 Sep 2022 08:01:01 +0000 (UTC) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MXW305QXdzmWJR; Wed, 21 Sep 2022 15:57:00 +0800 (CST) Received: from dggpemm100009.china.huawei.com (7.185.36.113) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 21 Sep 2022 16:00:56 +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; Wed, 21 Sep 2022 16:00:55 +0800 From: Liu Shixin To: Liu Zixian , Mike Kravetz , Muchun Song , "Andrew Morton" CC: , , Liu Shixin , Kefeng Wang Subject: [PATCH] mm: hugetlb: fix UAF in hugetlb_handle_userfault Date: Wed, 21 Sep 2022 16:34:40 +0800 Message-ID: <20220921083440.1267903-1-liushixin2@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.113.32] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm100009.china.huawei.com (7.185.36.113) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663747262; a=rsa-sha256; cv=none; b=Dw5noXYnpXOfHOz93a3jH5yNCRNVDnV0qnVBs66wxg73r4eV1Un6dT1z6+ioTsT37ZBGpv 6ul4mgs/MNzFnV1Ua67JffMYTK0dBE3OYWTkl4mJrto8w67apSzsmZr59pi0SYYOepmysf 6kv9PM2PUU8XWnMejHlOWJrgUTq1y7o= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf15.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=liushixin2@huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663747262; 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=6E92E7+gRcgAFDdyHFCnOP6eQmpFOWx5IeYyOacCBWM=; b=3JwTFXfPEvpD3FQ98c/Aj1LlQ80KF2xY1qOuabtJgbtGPY7pHcYdzqIm8aedWcXuna8H4i Tma4x11JO9v8dtVkdjaNFI1I010B50hysNjVvH9qhUBtdcXiXl7csQo37Q6wBuRBhUCvZR A7VsxFQvRQ2jmsTac8oruJAyBBtCTuA= X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9D409A0006 X-Stat-Signature: yrtx8sqthosbun5xtkrr8z95rjwbgdnk Authentication-Results: imf15.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf15.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=liushixin2@huawei.com X-Rspam-User: X-HE-Tag: 1663747261-401477 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] 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/20220921014457.1668-1-liuzixian4@huawei.com/ Reported-by: Liu Zixian Signed-off-by: Liu Shixin Signed-off-by: Kefeng Wang Reviewed-by: Sidhartha Kumar Reported-by: syzbot+193f9cee8638750b23cf@syzkaller.appspotmail.com --- 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;