From patchwork Tue Mar 22 08:34:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miaohe Lin X-Patchwork-Id: 12787165 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 310B3C433EF for ; Mon, 21 Mar 2022 11:59:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9D41F6B0072; Mon, 21 Mar 2022 07:59:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 983E86B0073; Mon, 21 Mar 2022 07:59:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 872106B0074; Mon, 21 Mar 2022 07:59:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0235.hostedemail.com [216.40.44.235]) by kanga.kvack.org (Postfix) with ESMTP id 78C506B0072 for ; Mon, 21 Mar 2022 07:59:46 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 24EF78A3C8 for ; Mon, 21 Mar 2022 11:59:46 +0000 (UTC) X-FDA: 79268249172.21.0761A97 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf09.hostedemail.com (Postfix) with ESMTP id 27F5F140012 for ; Mon, 21 Mar 2022 11:59:45 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KMY5W42NlzCr08; Mon, 21 Mar 2022 19:57:35 +0800 (CST) Received: from huawei.com (10.175.124.27) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 21 Mar 2022 19:59:40 +0800 From: Miaohe Lin To: , CC: , , , , Subject: [PATCH v2] mm/mempolicy: fix mpol_new leak in shared_policy_replace Date: Tue, 22 Mar 2022 16:34:56 +0800 Message-ID: <20220322083456.16563-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Queue-Id: 27F5F140012 X-Stat-Signature: xbweki3yn5gs3ntstk1nqwczwjnwxbe3 Authentication-Results: imf09.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf09.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspamd-Server: rspam03 X-HE-Tag: 1647863985-729911 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: If mpol_new is allocated but not used in restart loop, mpol_new will be freed via mpol_put before returning to the caller. But refcnt is not initialized yet, so mpol_put could not do the right things and might leak the unused mpol_new. This issue could be triggered easily with the below code snippet if there're many processes doing the below work at the same time: shmid = shmget((key_t)5566, 1024 * PAGE_SIZE, 0666|IPC_CREAT); shm = shmat(shmid, 0, 0); loop many times { mbind(shm, 1024 * PAGE_SIZE, MPOL_LOCAL, mask, maxnode, 0); mbind(shm + 128 * PAGE_SIZE, 128 * PAGE_SIZE, MPOL_DEFAULT, mask, maxnode, 0); } Fixes: 42288fe366c4 ("mm: mempolicy: Convert shared_policy mutex to spinlock") Signed-off-by: Miaohe Lin Cc: # 3.8 Acked-by: Michal Hocko Reported-by: kernel test robot Reported-by: kernel test robot --- v1->v2: Add reproducer snippet and Cc stable. Thanks Michal Hocko for review and comment! --- mm/mempolicy.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index a2516d31db6c..4cdd425b2752 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2733,6 +2733,7 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start, mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL); if (!mpol_new) goto err_out; + refcount_set(&mpol_new->refcnt, 1); goto restart; }