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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 14A27C4338F for ; Wed, 28 Jul 2021 14:57:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EAFEB60C3E for ; Wed, 28 Jul 2021 14:57:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236954AbhG1O50 (ORCPT ); Wed, 28 Jul 2021 10:57:26 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:7885 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235546AbhG1O5Y (ORCPT ); Wed, 28 Jul 2021 10:57:24 -0400 Received: from dggeme766-chm.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GZc9W5rdCz80gr; Wed, 28 Jul 2021 22:53:35 +0800 (CST) Received: from huawei.com (10.175.104.82) by dggeme766-chm.china.huawei.com (10.3.19.112) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Wed, 28 Jul 2021 22:57:20 +0800 From: Wang Hai To: , , , , , , , , , , CC: , Subject: [PATCH v2] mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() Date: Wed, 28 Jul 2021 22:56:55 +0800 Message-ID: <20210728145655.274476-1-wanghai38@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.104.82] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggeme766-chm.china.huawei.com (10.3.19.112) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When I use kfree_rcu() to free a large memory allocated by kmalloc_node(), the following dump occurs. BUG: kernel NULL pointer dereference, address: 0000000000000020 [...] Oops: 0000 [#1] SMP [...] Workqueue: events kfree_rcu_work RIP: 0010:__obj_to_index include/linux/slub_def.h:182 [inline] RIP: 0010:obj_to_index include/linux/slub_def.h:191 [inline] RIP: 0010:memcg_slab_free_hook+0x120/0x260 mm/slab.h:363 [...] Call Trace: kmem_cache_free_bulk+0x58/0x630 mm/slub.c:3293 kfree_bulk include/linux/slab.h:413 [inline] kfree_rcu_work+0x1ab/0x200 kernel/rcu/tree.c:3300 process_one_work+0x207/0x530 kernel/workqueue.c:2276 worker_thread+0x320/0x610 kernel/workqueue.c:2422 kthread+0x13d/0x160 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 When kmalloc_node() a large memory, page is allocated, not slab, so when freeing memory via kfree_rcu(), this large memory should not be used by memcg_slab_free_hook(), because memcg_slab_free_hook() is is used for slab. Using page_objcgs_check() instead of page_objcgs() in memcg_slab_free_hook() to fix this bug. Fixes: 270c6a71460e ("mm: memcontrol/slab: Use helpers to access slab page's memcg_data") Signed-off-by: Wang Hai --- v1->v2: Use page_objcgs_check() to fix this bug mm/slab.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slab.h b/mm/slab.h index 67e06637ff2e..59db4797acd4 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -339,7 +339,7 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s_orig, continue; page = virt_to_head_page(p[i]); - objcgs = page_objcgs(page); + objcgs = page_objcgs_check(page); if (!objcgs) continue; -- 2.17.1