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=-15.8 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 44872C4320A for ; Thu, 29 Jul 2021 21:53:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2EF7160FD7 for ; Thu, 29 Jul 2021 21:53:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234112AbhG2Vx7 (ORCPT ); Thu, 29 Jul 2021 17:53:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:38020 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234019AbhG2Vx7 (ORCPT ); Thu, 29 Jul 2021 17:53:59 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9AB1E60F48; Thu, 29 Jul 2021 21:53:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1627595635; bh=fAq3DahtlZ3nKcXaZ1PRHc7AS0nh1xwDLxj0akIi2SE=; h=Date:From:To:Subject:In-Reply-To:From; b=y9fCnhtLlQn2MjBdD543Ze6ppejDq3yc8oLuJsmJZ3euiMvLUVrjboLUiQhEfudHG VWyy6wxOR7sfT9A6GldSF7oKUeEGyTL3GgOd46/MW3eMjYkAgxc6SOZBXCA8FFkbgP WfAHpe92l1nSZrHw+GScbReHGEnc20UdSq01oYVU= Date: Thu, 29 Jul 2021 14:53:54 -0700 From: Andrew Morton To: akpm@linux-foundation.org, ast@kernel.org, cl@linux.com, guro@fb.com, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, shakeelb@google.com, songmuchun@bytedance.com, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, wanghai38@huawei.com, wangkefeng.wang@huawei.com Subject: [patch 7/7] mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() Message-ID: <20210729215354.cIhMlxeSy%akpm@linux-foundation.org> In-Reply-To: <20210729145259.24681c326dc3ed18194cf9e5@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: Wang Hai Subject: mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() 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. Link: https://lkml.kernel.org/r/20210728145655.274476-1-wanghai38@huawei.com Fixes: 270c6a71460e ("mm: memcontrol/slab: Use helpers to access slab page's memcg_data") Signed-off-by: Wang Hai Reviewed-by: Shakeel Butt Acked-by: Michal Hocko Acked-by: Roman Gushchin Reviewed-by: Kefeng Wang Reviewed-by: Muchun Song Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Vlastimil Babka Cc: Johannes Weiner Cc: Alexei Starovoitov Cc: Signed-off-by: Andrew Morton --- mm/slab.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/slab.h~mm-memcg-fix-null-pointer-dereference-in-memcg_slab_free_hook +++ a/mm/slab.h @@ -346,7 +346,7 @@ static inline void memcg_slab_free_hook( continue; page = virt_to_head_page(p[i]); - objcgs = page_objcgs(page); + objcgs = page_objcgs_check(page); if (!objcgs) continue; _