From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61BA83BBF6 for ; Tue, 15 Oct 2024 01:13:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728954820; cv=none; b=aQ9ZG+koOhtphj7bUY3ME4GcV71VeTqi85TOm8IgW1NtTMyhW+oZAYVd4Xp+v24yBKqV4Rr3btV2KNHQHVYiXz2gQ8WGwcThC2Q3TWzwldaNOVJfnqaqIrFSYpb4P2WsF4Lyg/kf1euaUHPT7BAGxAY5Ge+xzr0U15lv7ZWzrTk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728954820; c=relaxed/simple; bh=RD+NmBmnbXvJoCSN33M9E/PgG7qGxlMSfMggHwc/M20=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=FlmXsyeIyKx1dClNoKLdzhd6n/DwwQm0p6vFx/VhG4atX1vn72WSoAXwCPFADu7Gg4S+PysqXxRBiwnbsOSfdt1GrIVKzLoaScf7IbBb3mQdR/PWrZe7kr1z/6l8scvRAFkp4eDcsigjTUzCNJBIzoDa72fSye9GQtfL1US6oQY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4XSGKX4Plrz2DdZD; Tue, 15 Oct 2024 09:12:16 +0800 (CST) Received: from kwepemd100013.china.huawei.com (unknown [7.221.188.163]) by mail.maildlp.com (Postfix) with ESMTPS id 0B5901A016C; Tue, 15 Oct 2024 09:13:29 +0800 (CST) Received: from [10.67.109.79] (10.67.109.79) by kwepemd100013.china.huawei.com (7.221.188.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Tue, 15 Oct 2024 09:13:28 +0800 Message-ID: Date: Tue, 15 Oct 2024 09:13:27 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: shrinker: avoid memleak in alloc_shrinker_info To: "Kirill A. Shutemov" , Chen Ridong CC: , , , , , , , References: <20241014032336.482088-1-chenridong@huaweicloud.com> Content-Language: en-US From: chenridong In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemd100013.china.huawei.com (7.221.188.163) On 2024/10/14 19:29, Kirill A. Shutemov wrote: > On Mon, Oct 14, 2024 at 03:23:36AM +0000, Chen Ridong wrote: >> From: Chen Ridong >> >> A memleak was found as bellow: >> >> unreferenced object 0xffff8881010d2a80 (size 32): >> comm "mkdir", pid 1559, jiffies 4294932666 >> hex dump (first 32 bytes): >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 @............... >> backtrace (crc 2e7ef6fa): >> [] __kmalloc_node_noprof+0x394/0x470 >> [] alloc_shrinker_info+0x7b/0x1a0 >> [] mem_cgroup_css_online+0x11a/0x3b0 >> [] online_css+0x29/0xa0 >> [] cgroup_apply_control_enable+0x20d/0x360 >> [] cgroup_mkdir+0x168/0x5f0 >> [] kernfs_iop_mkdir+0x5e/0x90 >> [] vfs_mkdir+0x144/0x220 >> [] do_mkdirat+0x87/0x130 >> [] __x64_sys_mkdir+0x49/0x70 >> [] do_syscall_64+0x68/0x140 >> [] entry_SYSCALL_64_after_hwframe+0x76/0x7e >> >> In the alloc_shrinker_info function, when shrinker_unit_alloc return >> err, the info won't be freed. Just fix it. >> >> Fixes: 307bececcd12 ("mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}") >> Signed-off-by: Chen Ridong >> --- >> mm/shrinker.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/mm/shrinker.c b/mm/shrinker.c >> index dc5d2a6fcfc4..92270413190d 100644 >> --- a/mm/shrinker.c >> +++ b/mm/shrinker.c >> @@ -97,6 +97,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) >> >> err: >> mutex_unlock(&shrinker_mutex); >> + kvfree(info); >> free_shrinker_info(memcg); >> return -ENOMEM; >> } > > NAK. If in the future there going to one more error case after > rcu_assign_pointer() we will end up with double free. > > This should be safer: > > diff --git a/mm/shrinker.c b/mm/shrinker.c > index dc5d2a6fcfc4..763fd556bc7d 100644 > --- a/mm/shrinker.c > +++ b/mm/shrinker.c > @@ -87,8 +87,10 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) > if (!info) > goto err; > info->map_nr_max = shrinker_nr_max; > - if (shrinker_unit_alloc(info, NULL, nid)) > + if (shrinker_unit_alloc(info, NULL, nid)) { > + kvfree(info); > goto err; > + } > rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info); > } > mutex_unlock(&shrinker_mutex); This is what I sent in v1. Muchun thinks it's better to do the similar thing in the same way. Thanks, Ridong