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 6C56BC7618A for ; Mon, 20 Mar 2023 11:10:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230080AbjCTLJv (ORCPT ); Mon, 20 Mar 2023 07:09:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229913AbjCTLJb (ORCPT ); Mon, 20 Mar 2023 07:09:31 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2FC76E97 for ; Mon, 20 Mar 2023 04:05:37 -0700 (PDT) Received: from dggpemm500014.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4PgBhM3wgTzrVMm; Mon, 20 Mar 2023 19:04:35 +0800 (CST) Received: from [10.174.178.120] (10.174.178.120) by dggpemm500014.china.huawei.com (7.185.36.153) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Mon, 20 Mar 2023 19:05:34 +0800 Message-ID: <35ff7e03-2f6f-7a15-aae2-ff1784cd5274@huawei.com> Date: Mon, 20 Mar 2023 19:05:33 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 CC: , , , , Subject: Re: [PATCH v4 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Content-Language: en-US To: , References: <20230320024739.224850-1-mawupeng1@huawei.com> <20230320024739.224850-2-mawupeng1@huawei.com> <27b9cb5b-0118-f989-80c2-6a143a4232af@redhat.com> From: mawupeng In-Reply-To: <27b9cb5b-0118-f989-80c2-6a143a4232af@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.120] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/3/20 18:54, David Hildenbrand wrote: > On 20.03.23 03:47, Wupeng Ma wrote: >> From: Ma Wupeng >> >> While testing mlock, we have a problem if the len of mlock is ULONG_MAX. >> The return value of mlock is zero. But nothing will be locked since the >> len in do_mlock overflows to zero due to the following code in mlock: >> >>    len = PAGE_ALIGN(len + (offset_in_page(start))); >> >> The same problem happens in munlock. >> >> Add new check and return -EINVAL to fix this overflowing scenarios since >> they are absolutely wrong. > > Thinking again, wouldn't we reject mlock(0, ULONG_MAX) now as well? Thanks for reviewing. I will test this and resend & reply this. > >> >> Signed-off-by: Ma Wupeng >> --- >>   mm/mlock.c | 8 ++++++++ >>   1 file changed, 8 insertions(+) >> >> diff --git a/mm/mlock.c b/mm/mlock.c >> index 617469fce96d..eb68476da497 100644 >> --- a/mm/mlock.c >> +++ b/mm/mlock.c >> @@ -568,6 +568,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla >>       unsigned long locked; >>       unsigned long lock_limit; >>       int error = -ENOMEM; >> +    size_t old_len = len; >>         start = untagged_addr(start); >>   @@ -577,6 +578,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla >>       len = PAGE_ALIGN(len + (offset_in_page(start))); >>       start &= PAGE_MASK; >>   +    if (old_len != 0 && len == 0) > > if (old_len && !len) > >> +        return -EINVAL; >> + >>       lock_limit = rlimit(RLIMIT_MEMLOCK); >>       lock_limit >>= PAGE_SHIFT; >>       locked = len >> PAGE_SHIFT; >> @@ -631,12 +635,16 @@ SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags) >>   SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) >>   { >>       int ret; >> +    size_t old_len = len; >>         start = untagged_addr(start); >>         len = PAGE_ALIGN(len + (offset_in_page(start))); >>       start &= PAGE_MASK; >>   +    if (old_len != 0 && len == 0) > > if (old_len && !len) Sorry for wasting your time. I send the wrong version of this patchset, this is the older version. > >> +        return -EINVAL; >> + >>       if (mmap_write_lock_killable(current->mm)) >>           return -EINTR; >>       ret = apply_vma_lock_flags(start, len, 0); >