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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB82DC77B76 for ; Fri, 21 Apr 2023 19:44:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232480AbjDUToX (ORCPT ); Fri, 21 Apr 2023 15:44:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232925AbjDUToX (ORCPT ); Fri, 21 Apr 2023 15:44:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0F4C19A1 for ; Fri, 21 Apr 2023 12:44:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8D4CF65292 for ; Fri, 21 Apr 2023 19:44:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD092C433EF; Fri, 21 Apr 2023 19:44:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1682106261; bh=8fqKKXWCq37l6m1DGMTzrEC5wWrGq3Fvcu0M6jrb6xQ=; h=Date:To:From:Subject:From; b=g4DqP0BYuP8AWXi219oJsiLq4iyJjkypBRLlPcHhtX1TnzimxpH/fIF5qt8Q/D9ge GSKyojFvd/cqO8smyAoBnSbGTpSrgU06c/vBTz8PJuDnjyl6G3FnicPa8cM1P8LlN1 cb4/vfOCBQ23aYYjWGacYB+0/CTCwuflVvYq1G/o= Date: Fri, 21 Apr 2023 12:44:20 -0700 To: mm-commits@vger.kernel.org, shakeelb@google.com, muchun.song@linux.dev, mhocko@kernel.org, hannes@cmpxchg.org, dvyukov@google.com, roman.gushchin@linux.dev, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-kmem-fix-a-null-pointer-dereference-in-obj_stock_flush_required.patch added to mm-unstable branch Message-Id: <20230421194420.DD092C433EF@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() has been added to the -mm mm-unstable branch. Its filename is mm-kmem-fix-a-null-pointer-dereference-in-obj_stock_flush_required.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kmem-fix-a-null-pointer-dereference-in-obj_stock_flush_required.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Roman Gushchin Subject: mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() Date: Fri, 21 Apr 2023 10:40:54 -0700 KCSAN found an issue in obj_stock_flush_required(): stock->cached_objcg can be reset between the check and dereference: ================================================================== BUG: KCSAN: data-race in drain_all_stock / drain_obj_stock write to 0xffff888237c2a2f8 of 8 bytes by task 19625 on cpu 0: drain_obj_stock+0x408/0x4e0 mm/memcontrol.c:3306 refill_obj_stock+0x9c/0x1e0 mm/memcontrol.c:3340 obj_cgroup_uncharge+0xe/0x10 mm/memcontrol.c:3408 memcg_slab_free_hook mm/slab.h:587 [inline] __cache_free mm/slab.c:3373 [inline] __do_kmem_cache_free mm/slab.c:3577 [inline] kmem_cache_free+0x105/0x280 mm/slab.c:3602 __d_free fs/dcache.c:298 [inline] dentry_free fs/dcache.c:375 [inline] __dentry_kill+0x422/0x4a0 fs/dcache.c:621 dentry_kill+0x8d/0x1e0 dput+0x118/0x1f0 fs/dcache.c:913 __fput+0x3bf/0x570 fs/file_table.c:329 ____fput+0x15/0x20 fs/file_table.c:349 task_work_run+0x123/0x160 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xcf/0xe0 kernel/entry/common.c:171 exit_to_user_mode_prepare+0x6a/0xa0 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd read to 0xffff888237c2a2f8 of 8 bytes by task 19632 on cpu 1: obj_stock_flush_required mm/memcontrol.c:3319 [inline] drain_all_stock+0x174/0x2a0 mm/memcontrol.c:2361 try_charge_memcg+0x6d0/0xd10 mm/memcontrol.c:2703 try_charge mm/memcontrol.c:2837 [inline] mem_cgroup_charge_skmem+0x51/0x140 mm/memcontrol.c:7290 sock_reserve_memory+0xb1/0x390 net/core/sock.c:1025 sk_setsockopt+0x800/0x1e70 net/core/sock.c:1525 udp_lib_setsockopt+0x99/0x6c0 net/ipv4/udp.c:2692 udp_setsockopt+0x73/0xa0 net/ipv4/udp.c:2817 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3668 __sys_setsockopt+0x1c3/0x230 net/socket.c:2271 __do_sys_setsockopt net/socket.c:2282 [inline] __se_sys_setsockopt net/socket.c:2279 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2279 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0xffff8881382d52c0 -> 0xffff888138893740 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 19632 Comm: syz-executor.0 Not tainted 6.3.0-rc2-syzkaller-00387-g534293368afa #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Fix it by reading the cached_objcg with READ_ONCE(). Link: https://lkml.kernel.org/r/20230421174054.3434533-1-roman.gushchin@linux.dev Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") Signed-off-by: Roman Gushchin Reported-by: syzbot+774c29891415ab0fd29d@syzkaller.appspotmail.com Reported-by: Dmitry Vyukov Link: https://lore.kernel.org/linux-mm/CACT4Y+ZfucZhM60YPphWiCLJr6+SGFhT+jjm8k1P-a_8Kkxsjg@mail.gmail.com/T/#t Cc: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Shakeel Butt Signed-off-by: Andrew Morton --- mm/memcontrol.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/memcontrol.c~mm-kmem-fix-a-null-pointer-dereference-in-obj_stock_flush_required +++ a/mm/memcontrol.c @@ -3343,10 +3343,11 @@ static struct obj_cgroup *drain_obj_stoc static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg) { + struct obj_cgroup *objcg = READ_ONCE(stock->cached_objcg); struct mem_cgroup *memcg; - if (stock->cached_objcg) { - memcg = obj_cgroup_memcg(stock->cached_objcg); + if (objcg) { + memcg = obj_cgroup_memcg(objcg); if (memcg && mem_cgroup_is_descendant(memcg, root_memcg)) return true; } _ Patches currently in -mm which might be from roman.gushchin@linux.dev are mm-kmem-fix-a-null-pointer-dereference-in-obj_stock_flush_required.patch