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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B7C6C433F5 for ; Mon, 16 May 2022 09:47:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F14046B0071; Mon, 16 May 2022 05:47:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EC3926B0072; Mon, 16 May 2022 05:47:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D8B436B0073; Mon, 16 May 2022 05:47:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C99B76B0071 for ; Mon, 16 May 2022 05:47:31 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 95826807F3 for ; Mon, 16 May 2022 09:47:31 +0000 (UTC) X-FDA: 79471128702.16.6ACEC2F Received: from mail-pf1-f195.google.com (mail-pf1-f195.google.com [209.85.210.195]) by imf17.hostedemail.com (Postfix) with ESMTP id 9CE74400C6 for ; Mon, 16 May 2022 09:47:08 +0000 (UTC) Received: by mail-pf1-f195.google.com with SMTP id k16so6784900pff.5 for ; Mon, 16 May 2022 02:47:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=YHaY3VzzTKl05Ylig5G4revSeCBrE0n2SgEWey+VV4c=; b=kJYGrFZKUFrWk0ImWW0YnAKs8rcQzfSr2AwwcnEDXieIovOXoMXhPfHwkPrRr2ZH7o xG4giXUDJD8ISDP6iPnb9oDfLIB3221ksRJ3Rc9/Mv6j99u+uC7PEKZx6eC3T0wZU3sv 2KcBpyQhdSwtSPFTH022wws+PNTjY8P5kf8QzLrDotBClqNmhO+tZpxCwC1K69P2bk1J DSR63mJwu57lsyUm8sjZv1CqSyMvJvMwNy6o9ELSPh2UdM2bVjfNA1+F4NUKYiXcrb3X 8bUu7QGJbpkb8qHWeSzKsZ5qhXTxtmauGydQ60t8cWQX0N5KZyAnIisHArUfo2x8Qryy ORvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=YHaY3VzzTKl05Ylig5G4revSeCBrE0n2SgEWey+VV4c=; b=rkvf0fU4x7J4ZPn75zNLHWWt7jZHGG/0hB7PZs4JCVoUO/SRaAKYePoBFD74LS6jX+ ADHSyDxaskzmShH6d/W8ftfSQYb/IviGB8LnmrOdAkquUl77DDz9PjjN0VYQVfoiW1zm +lu24HsPx9y844I0jbR5dV1AeugQjL/31EPykC53jDpyPTeqAhcQ7TJ9aqRgPvmf3xzu 8mE8JeRpqimruMohYrjkw1F/gf4fj4QeX1KAyBTf1ZMQWB8ZqVaKcbt6vyBTxlHbTPq+ txDuSnsi93EZnj8wUMOp3JR6kWmZyQcymKJ961w9uEgtAMFMMrvV4AnsDrp5nSMTd/PI KhEA== X-Gm-Message-State: AOAM531NUJFuWJEh9pvJ59J7Oi4SkiJXZ08LOV+EyuNjxJMGivTnMmv6 yEPrUUxdurtADwY5zLbFRKA= X-Google-Smtp-Source: ABdhPJzsEPBimYWFMWXuaEdMh9q0tebRm3TOASpMfV8I3pGO3mHPFBU2WdI48Hy0Ww1RHk20d2n66A== X-Received: by 2002:a05:6a00:e8e:b0:4fa:a52f:59cf with SMTP id bo14-20020a056a000e8e00b004faa52f59cfmr16610949pfb.84.1652694450244; Mon, 16 May 2022 02:47:30 -0700 (PDT) Received: from localhost ([152.70.90.187]) by smtp.gmail.com with ESMTPSA id u23-20020a1709026e1700b0015e8d4eb1ffsm6639952plk.73.2022.05.16.02.47.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 May 2022 02:47:29 -0700 (PDT) Date: Mon, 16 May 2022 17:47:26 +0800 From: Wang Cheng To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, syzbot+ad1b8c404f0959c4bfcc@syzkaller.appspotmail.com Subject: Re: [PATCH] mm/mempolicy: fix uninit-value in mpol_rebind_policy() Message-ID: <20220516094726.b5rrsjg7rvei2od5@ppc.localdomain> References: <20220512123428.fq3wofedp6oiotd4@ppc.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220512123428.fq3wofedp6oiotd4@ppc.localdomain> Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=kJYGrFZK; spf=pass (imf17.hostedemail.com: domain of wanngchenng@gmail.com designates 209.85.210.195 as permitted sender) smtp.mailfrom=wanngchenng@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9CE74400C6 X-Stat-Signature: 8b4yzob7oqncq88nipu4qewnupu3hc69 X-HE-Tag: 1652694428-918692 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 22/05/12 08:34PM, Wang Cheng wrote: > mpol_set_nodemask()(mm/mempolicy.c) does not set up nodemask when > pol->mode is MPOL_LOCAL. Check pol->mode before access > pol->w.cpuset_mems_allowed in mpol_rebind_policy()(mm/mempolicy.c). > > BUG: KMSAN: uninit-value in mpol_rebind_policy mm/mempolicy.c:352 [inline] > BUG: KMSAN: uninit-value in mpol_rebind_task+0x2ac/0x2c0 mm/mempolicy.c:368 > mpol_rebind_policy mm/mempolicy.c:352 [inline] > mpol_rebind_task+0x2ac/0x2c0 mm/mempolicy.c:368 > cpuset_change_task_nodemask kernel/cgroup/cpuset.c:1711 [inline] > cpuset_attach+0x787/0x15e0 kernel/cgroup/cpuset.c:2278 > cgroup_migrate_execute+0x1023/0x1d20 kernel/cgroup/cgroup.c:2515 > cgroup_migrate kernel/cgroup/cgroup.c:2771 [inline] > cgroup_attach_task+0x540/0x8b0 kernel/cgroup/cgroup.c:2804 > __cgroup1_procs_write+0x5cc/0x7a0 kernel/cgroup/cgroup-v1.c:520 > cgroup1_tasks_write+0x94/0xb0 kernel/cgroup/cgroup-v1.c:539 > cgroup_file_write+0x4c2/0x9e0 kernel/cgroup/cgroup.c:3852 > kernfs_fop_write_iter+0x66a/0x9f0 fs/kernfs/file.c:296 > call_write_iter include/linux/fs.h:2162 [inline] > new_sync_write fs/read_write.c:503 [inline] > vfs_write+0x1318/0x2030 fs/read_write.c:590 > ksys_write+0x28b/0x510 fs/read_write.c:643 > __do_sys_write fs/read_write.c:655 [inline] > __se_sys_write fs/read_write.c:652 [inline] > __x64_sys_write+0xdb/0x120 fs/read_write.c:652 > do_syscall_x64 arch/x86/entry/common.c:51 [inline] > do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Uninit was created at: > slab_post_alloc_hook mm/slab.h:524 [inline] > slab_alloc_node mm/slub.c:3251 [inline] > slab_alloc mm/slub.c:3259 [inline] > kmem_cache_alloc+0x902/0x11c0 mm/slub.c:3264 > mpol_new mm/mempolicy.c:293 [inline] > do_set_mempolicy+0x421/0xb70 mm/mempolicy.c:853 > kernel_set_mempolicy mm/mempolicy.c:1504 [inline] > __do_sys_set_mempolicy mm/mempolicy.c:1510 [inline] > __se_sys_set_mempolicy+0x44c/0xb60 mm/mempolicy.c:1507 > __x64_sys_set_mempolicy+0xd8/0x110 mm/mempolicy.c:1507 > do_syscall_x64 arch/x86/entry/common.c:51 [inline] > do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > KMSAN: uninit-value in mpol_rebind_task (2) > https://syzkaller.appspot.com/bug?id=d6eb90f952c2a5de9ea718a1b873c55cb13b59dc > > Reported-and-tested-by: syzbot+217f792c92599518a2ab@syzkaller.appspotmail.com > Signed-off-by: Wang Cheng > --- > The uninit-value is pol->w.cpuset_mems_allowed in > mpol_rebind_policy(). > > While syzkaller reproducer runs, I notice pol->mode is 4(MPOL_LOCAL) in > mpol_set_nodemask() > do_set_mempolicy()(mm/mempolicy.c) > that `nodemask` in `pol` is not initialized, which will be accessed in > mpol_rebind_policy(). > > mm/mempolicy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 10e9c87260ed..18b74f02da71 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -347,7 +347,7 @@ static void mpol_rebind_preferred(struct mempolicy *pol, > */ > static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask) > { > - if (!pol) > + if (!pol || pol->mode == MPOL_LOCAL) > return; > if (!mpol_store_user_nodemask(pol) && > nodes_equal(pol->w.cpuset_mems_allowed, *newmask)) > -- > 2.30.2 > Hi Andrew, Thank you for fixing the commit message. This patch seems to fix below bug too. KMSAN: uninit-value in mpol_rebind_mm (2) https://syzkaller.appspot.com/bug?id=f2fecd0d7013f54ec4162f60743a2b28df40926b The uninit-value is pol->w.cpuset_mems_allowed in mpol_rebind_policy(). When syzkaller reproducer runs to the beginning of mpol_new(), mpol_new() mm/mempolicy.c do_mbind() mm/mempolicy.c kernel_mbind() mm/mempolicy.c `mode` is 1(MPOL_PREFERRED), nodes_empty(*nodes) is `true` and `flags` is 0. Then mode = MPOL_LOCAL; ... policy->mode = mode; policy->flags = flags; will be executed. So in mpol_set_nodemask(), mpol_set_nodemask() mm/mempolicy.c do_mbind() kernel_mbind() pol->mode is 4(MPOL_LOCAL), that `nodemask` in `pol` is not initialized, which will be accessed in mpol_rebind_policy(). IIUC, "#syz fix: mm/mempolicy: fix uninit-value in mpol_rebind_policy()" could be sent to syzbot+ad1b8c404f0959c4bfcc@syzkaller.appspotmail.com to attach the fixing commit to the bug. WDYT? thanks, - w