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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D3B89C56202 for ; Thu, 26 Nov 2020 06:34:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8455A20DD4 for ; Thu, 26 Nov 2020 06:34:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388086AbgKZGeM (ORCPT ); Thu, 26 Nov 2020 01:34:12 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:8403 "EHLO szxga07-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732690AbgKZGeM (ORCPT ); Thu, 26 Nov 2020 01:34:12 -0500 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4ChSdN3y5Sz73qx; Thu, 26 Nov 2020 14:33:44 +0800 (CST) Received: from [10.174.178.154] (10.174.178.154) by smtp.huawei.com (10.3.19.205) with Microsoft SMTP Server (TLS) id 14.3.487.0; Thu, 26 Nov 2020 14:33:56 +0800 Subject: Re: [PATCH] tomoyo: Avoid potential null pointer access To: Tetsuo Handa CC: , , , , References: <20201125121043.107662-1-zhengzengkai@huawei.com> From: Zheng Zengkai Message-ID: <01d29bbf-9d77-c787-b2c2-d88a6a5047f7@huawei.com> Date: Thu, 26 Nov 2020 14:33:55 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.154] X-CFilter-Loop: Reflected Precedence: bulk List-ID: Hello, Tetsuo Got it , Thank you for your explanation. > Hello, Zheng. > > Thank you for a patch, but I won't apply this patch. > Expected behavior is that tomoyo_warn_oom() is called > if tomoyo_memory_ok() is called with entry == NULL. > > Adding __GFP_NOWARN might be OK, but returning without tomoyo_warn_oom() is NG. > > On 2020/11/25 21:10, Zheng Zengkai wrote: >> Calls to kzalloc() should be null-checked in order to avoid >> any potential failures or unnecessary code execution. >> Fix this by adding null checks for _entry_ right after allocation. >> >> Fixes: 57c2590fb7fd ("TOMOYO: Update profile structure") >> Reported-by: Hulk Robot >> Signed-off-by: Zheng Zengkai > Nacked-by: Tetsuo Handa As your say,  I found the function tomoyo_assign_namespace( ) in security/tomoyo/domain.c has the similar situation, Can I add __GFP_NOWARN for both and remove the null check for _entry_ in tomoyo_assign_namespace( )? diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c index 4bee32bfe16d..bc54d3c8c70a 100644 --- a/security/tomoyo/common.c +++ b/security/tomoyo/common.c @@ -498,7 +498,7 @@ static struct tomoyo_profile *tomoyo_assign_profile         ptr = ns->profile_ptr[profile];         if (ptr)                 return ptr; -       entry = kzalloc(sizeof(*entry), GFP_NOFS); +       entry = kzalloc(sizeof(*entry), GFP_NOFS | __GFP_NOWARN);         if (mutex_lock_interruptible(&tomoyo_policy_lock))                 goto out;         ptr = ns->profile_ptr[profile]; diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c index dc4ecc0b2038..c6e5cc5cc7cd 100644 --- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -473,9 +473,7 @@ struct tomoyo_policy_namespace *tomoyo_assign_namespace(const char *domainname)                 return ptr;         if (len >= TOMOYO_EXEC_TMPSIZE - 10 || !tomoyo_domain_def(domainname))                 return NULL; -       entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS); -       if (!entry) -               return NULL; +       entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS | __GFP_NOWARN);         if (mutex_lock_interruptible(&tomoyo_policy_lock))                 goto out;         ptr = tomoyo_find_namespace(domainname, len); >> --- >> security/tomoyo/common.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c >> index 4bee32bfe16d..99b4fafcb100 100644 >> --- a/security/tomoyo/common.c >> +++ b/security/tomoyo/common.c >> @@ -499,6 +499,8 @@ static struct tomoyo_profile *tomoyo_assign_profile >> if (ptr) >> return ptr; >> entry = kzalloc(sizeof(*entry), GFP_NOFS); >> + if (!entry) >> + return NULL; >> if (mutex_lock_interruptible(&tomoyo_policy_lock)) >> goto out; >> ptr = ns->profile_ptr[profile]; >> > . >