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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 52DF1C4338F for ; Thu, 29 Jul 2021 06:04:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3BA6C61042 for ; Thu, 29 Jul 2021 06:04:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234354AbhG2GEb (ORCPT ); Thu, 29 Jul 2021 02:04:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234093AbhG2GEV (ORCPT ); Thu, 29 Jul 2021 02:04:21 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB639C061757 for ; Wed, 28 Jul 2021 23:04:18 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id q17-20020a17090a2e11b02901757deaf2c8so7846783pjd.0 for ; Wed, 28 Jul 2021 23:04:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=gqlOu5w7sIF9m7Ex8akMtGucE3AKmn8iiHCycTTM/xE=; b=ph5LVGOXWqyvIdu2y1OP4WXRoj1hjrxn2tMBtanm0fgVIqf/Ci5vZR+j5hFfnpT6l6 7pXTYJQm5/AgQ7wbdxQK9FLkQKfoo5kDHqsNp8v9VYzzNUfrjgsuV3SHqMsInWz1/Ehm 3brKiO0WsbndMAUkGXTuc3TBBBXR3zDBKfnF8qD8Pr0l/u7bKsUsUeDWNQJymO3GjFEj 9TKvtt9JJkeLrP3dePxuRwCmQj1rN9dTo1gEMzlQZBRilTrlg9MHO4Sz+wHXIHu6+3H8 TyKdyH7bxBfhvYUNHU9D0ZwTkBPNOUhzqqq8FDcdYdIwVXLQuIBCqNZOEH2F/8xTvfz4 JWTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=gqlOu5w7sIF9m7Ex8akMtGucE3AKmn8iiHCycTTM/xE=; b=nvDsirOIsMP15/pFBQRvhVG6cSPx4TFzwKn7Ek/QGyjT+U4AxtZTNaZBobJZ9YojZl fGuFHgLoieIZ4vshFr/0Eb909qhWZy6kob58X+7k6ZBBMTApbHtzEYiEPD1TA344Yo+X mFs1jgXbJbYhc56x4gHZ+zzVVF9TjHbOpu5IEZEYBGqFOkV5dEiiP0gnsmxSFFlynUu5 1ZgIe8KXqZla4XKN9CSnwzKUKp86NTw+dYC7/XnS+a4bgcDeK2xQmqpdZfHlzORNlZci ub6Czl6ztvLapsVOyC4Twjn3U5qXTKHNzrh7CqamYaX31MDcdArQmpUxJRw5CmdJyZKO g/1Q== X-Gm-Message-State: AOAM53023proKcYdh6NfB9Jb7gX6tH49onc0G58LUviVyIWV9FeCGOPP msry0g6Mh88kwokoD9xjXzw7QBmoGr18H72FKuw7Aw== X-Google-Smtp-Source: ABdhPJzDYXlUsa81+9TOdegbgF8dMAhSsTVDVOveJdyatsUa0SeIZyLEktiOkLl3eKARlGFPUGBpGpqw1eAxyKQ27MY= X-Received: by 2002:a17:90a:9b13:: with SMTP id f19mr3547754pjp.229.1627538658277; Wed, 28 Jul 2021 23:04:18 -0700 (PDT) MIME-Version: 1.0 References: <20210728145655.274476-1-wanghai38@huawei.com> In-Reply-To: <20210728145655.274476-1-wanghai38@huawei.com> From: Muchun Song Date: Thu, 29 Jul 2021 14:03:39 +0800 Message-ID: Subject: Re: [PATCH v2] mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() To: Wang Hai Cc: Christoph Lameter , Pekka Enberg , Roman Gushchin , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Johannes Weiner , Shakeel Butt , Alexei Starovoitov , Kefeng Wang , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 28, 2021 at 10:57 PM Wang Hai wrote: > > 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 More simpler than v1. Thanks. Reviewed-by: Muchun Song