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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 A767EC17441 for ; Mon, 11 Nov 2019 19:01:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 80B3E222C1 for ; Mon, 11 Nov 2019 19:01:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573498896; bh=jkHfvIqWuWJ2ECCbX2yk49tBLr6K1O/+rweHBYy0hDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FK3rmYDu43M/5ad6DaUfh0L0x6mKdxCBaYKHl+Jt/PmZy8PCrYCRfC4tdF1OT/jF7 1eYh0iKUrBBggabglmluPHo1O6jsM5SJRIW+fxvBA6NjotLTRiF3FuLfGOzAMsGoff XtozCdsin8yYPETLFg6AKQfXjHnr3d+5uBS9egZg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729396AbfKKSu7 (ORCPT ); Mon, 11 Nov 2019 13:50:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:44908 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728474AbfKKSu6 (ORCPT ); Mon, 11 Nov 2019 13:50:58 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A91DA214E0; Mon, 11 Nov 2019 18:50:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573498257; bh=jkHfvIqWuWJ2ECCbX2yk49tBLr6K1O/+rweHBYy0hDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XIN4pIvFXAbmOCEh+oh+ncUPA5o5fZghZpyXMnCDFAbk9PRAFJYAcvFvt9T7xRGzu dj+cvCtyOTBrXZraPoH8rw7ndajtGTgCR4HE754ZMtxjgfsLZ6fMjxUZj+F2ZQ1VSb 43QvsR7aeNbeFtSvPerIENl7kym5pdsCPDLX6R1Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shakeel Butt , syzbot+515d5bcfe179cdf049b2@syzkaller.appspotmail.com, Roman Gushchin , Michal Hocko , Johannes Weiner , Vladimir Davydov , Andrew Morton , Linus Torvalds Subject: [PATCH 5.3 028/193] mm: memcontrol: fix NULL-ptr deref in percpu stats flush Date: Mon, 11 Nov 2019 19:26:50 +0100 Message-Id: <20191111181502.357208519@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191111181459.850623879@linuxfoundation.org> References: <20191111181459.850623879@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Shakeel Butt commit 7961eee3978475fd9e8626137f88595b1ca05856 upstream. __mem_cgroup_free() can be called on the failure path in mem_cgroup_alloc(). However memcg_flush_percpu_vmstats() and memcg_flush_percpu_vmevents() which are called from __mem_cgroup_free() access the fields of memcg which can potentially be null if called from failure path from mem_cgroup_alloc(). Indeed syzbot has reported the following crash: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 30393 Comm: syz-executor.1 Not tainted 5.4.0-rc2+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:memcg_flush_percpu_vmstats+0x4ae/0x930 mm/memcontrol.c:3436 Code: 05 41 89 c0 41 0f b6 04 24 41 38 c7 7c 08 84 c0 0f 85 5d 03 00 00 44 3b 05 33 d5 12 08 0f 83 e2 00 00 00 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 0f 85 91 03 00 00 48 8b 85 10 fe ff ff 48 8b b0 90 RSP: 0018:ffff888095c27980 EFLAGS: 00010206 RAX: 0000000000000012 RBX: ffff888095c27b28 RCX: ffffc90008192000 RDX: 0000000000040000 RSI: ffffffff8340fae7 RDI: 0000000000000007 RBP: ffff888095c27be0 R08: 0000000000000000 R09: ffffed1013f0da33 R10: ffffed1013f0da32 R11: ffff88809f86d197 R12: fffffbfff138b760 R13: dffffc0000000000 R14: 0000000000000090 R15: 0000000000000007 FS: 00007f5027170700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000710158 CR3: 00000000a7b18000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __mem_cgroup_free+0x1a/0x190 mm/memcontrol.c:5021 mem_cgroup_free mm/memcontrol.c:5033 [inline] mem_cgroup_css_alloc+0x3a1/0x1ae0 mm/memcontrol.c:5160 css_create kernel/cgroup/cgroup.c:5156 [inline] cgroup_apply_control_enable+0x44d/0xc40 kernel/cgroup/cgroup.c:3119 cgroup_mkdir+0x899/0x11b0 kernel/cgroup/cgroup.c:5401 kernfs_iop_mkdir+0x14d/0x1d0 fs/kernfs/dir.c:1124 vfs_mkdir+0x42e/0x670 fs/namei.c:3807 do_mkdirat+0x234/0x2a0 fs/namei.c:3830 __do_sys_mkdir fs/namei.c:3846 [inline] __se_sys_mkdir fs/namei.c:3844 [inline] __x64_sys_mkdir+0x5c/0x80 fs/namei.c:3844 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixing this by moving the flush to mem_cgroup_free as there is no need to flush anything if we see failure in mem_cgroup_alloc(). Link: http://lkml.kernel.org/r/20191018165231.249872-1-shakeelb@google.com Fixes: bb65f89b7d3d ("mm: memcontrol: flush percpu vmevents before releasing memcg") Fixes: c350a99ea2b1 ("mm: memcontrol: flush percpu vmstats before releasing memcg") Signed-off-by: Shakeel Butt Reported-by: syzbot+515d5bcfe179cdf049b2@syzkaller.appspotmail.com Reviewed-by: Roman Gushchin Cc: Michal Hocko Cc: Johannes Weiner Cc: Vladimir Davydov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memcontrol.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4763,12 +4763,6 @@ static void __mem_cgroup_free(struct mem { int node; - /* - * Flush percpu vmstats and vmevents to guarantee the value correctness - * on parent's and all ancestor levels. - */ - memcg_flush_percpu_vmstats(memcg, false); - memcg_flush_percpu_vmevents(memcg); for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); free_percpu(memcg->vmstats_percpu); @@ -4779,6 +4773,12 @@ static void __mem_cgroup_free(struct mem static void mem_cgroup_free(struct mem_cgroup *memcg) { memcg_wb_domain_exit(memcg); + /* + * Flush percpu vmstats and vmevents to guarantee the value correctness + * on parent's and all ancestor levels. + */ + memcg_flush_percpu_vmstats(memcg, false); + memcg_flush_percpu_vmevents(memcg); __mem_cgroup_free(memcg); }