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=unavailable 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 D60C1C433E0 for ; Wed, 24 Feb 2021 20:08:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93C8264F09 for ; Wed, 24 Feb 2021 20:08:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234917AbhBXUIF (ORCPT ); Wed, 24 Feb 2021 15:08:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:56272 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235287AbhBXUHZ (ORCPT ); Wed, 24 Feb 2021 15:07:25 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4B16764E60; Wed, 24 Feb 2021 20:07:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614197226; bh=U1XGcjm1zL4VDArObARHXrQYuQHUmmj/NdRZmLmtHbA=; h=Date:From:To:Subject:In-Reply-To:From; b=MWk1jijJ/85bjsjdSUeR0RYLYUpw9Gu06BeEbQHI94ruVpkkPSszUEzfSAIL+7tKv zanTGZBk0+w2SFhcrNBXrFIP61wxNfwxSG81jeA98L57yOX8R5kXMzuSt9RfbKpDsF wGo4W8AqQuiUBb00wy4WZhjwYfQNx+pAKbkbWxEw= Date: Wed, 24 Feb 2021 12:07:05 -0800 From: Andrew Morton To: akpm@linux-foundation.org, linmiaohe@huawei.com, linux-mm@kvack.org, louhongxiang@huawei.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 117/173] mm/hugetlb: fix use after free when subpool max_hpages accounting is not enabled Message-ID: <20210224200705.o8J0hqp8s%akpm@linux-foundation.org> In-Reply-To: <20210224115824.1e289a6895087f10c41dd8d6@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Miaohe Lin Subject: mm/hugetlb: fix use after free when subpool max_hpages accounting is not enabled If a hugetlbfs filesystem is created with the min_size option and without the size option, used_hpages is always 0 and might lead to release subpool prematurely because it indicates no pages are used now while there might be. In order to fix this issue, we should check used_hpages == 0 iff max_hpages accounting is enabled. As max_hpages accounting should be enabled in most common case, this is not worth a Cc stable. [mike.kravetz@oracle.com: new changelog] Link: https://lkml.kernel.org/r/20210126115510.53374-1-linmiaohe@huawei.com Signed-off-by: Hongxiang Lou Signed-off-by: Miaohe Lin Reviewed-by: Mike Kravetz Signed-off-by: Andrew Morton --- mm/hugetlb.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/mm/hugetlb.c~mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled +++ a/mm/hugetlb.c @@ -97,16 +97,26 @@ static inline void ClearPageHugeFreed(st /* Forward declaration */ static int hugetlb_acct_memory(struct hstate *h, long delta); -static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) +static inline bool subpool_is_free(struct hugepage_subpool *spool) { - bool free = (spool->count == 0) && (spool->used_hpages == 0); + if (spool->count) + return false; + if (spool->max_hpages != -1) + return spool->used_hpages == 0; + if (spool->min_hpages != -1) + return spool->rsv_hpages == spool->min_hpages; + + return true; +} +static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) +{ spin_unlock(&spool->lock); /* If no pages are used, and no other handles to the subpool * remain, give up any reservations based on minimum size and * free the subpool */ - if (free) { + if (subpool_is_free(spool)) { if (spool->min_hpages != -1) hugetlb_acct_memory(spool->hstate, -spool->min_hpages); _