Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20180326215522.GA409@bombadil.infradead.org>
References: <1513172572-16724-1-git-send-email-thunder.leizhen@huawei.com>
 <20171213141112.GA11217@bombadil.infradead.org> <x49y3m6a90r.fsf@segfault.boston.devel.redhat.com>
 <20171213193100.GA19700@bombadil.infradead.org> <5A31ED86.5000800@huawei.com>
 <20180102145155.GD8222@bombadil.infradead.org> <x49tvvqdfhu.fsf@segfault.boston.devel.redhat.com>
 <CAK8P3a3jb1cJEiyHA-G_HgmMFoN4Lb3YVnXzLkX+tUysd_YZgw@mail.gmail.com> <20180326215522.GA409@bombadil.infradead.org>
From:   Deepa Dinamani <deepa.kernel@gmail.com>
Date:   Mon, 26 Mar 2018 21:43:03 -0700
Message-ID: <CABeXuvqk1npq6ROEyF6O-uedkM1OV-zyfeAUcj3yeS-WP6GMQg@mail.gmail.com>
Subject: Re: [PATCH 1/1] aio: make sure the input "timeout" value is valid
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Arnd Bergmann <arnd@arndb.de>, Jeff Moyer <jmoyer@redhat.com>,
        "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Benjamin LaHaise <bcrl@kvack.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-aio <linux-aio@kvack.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Tianhong Ding <dingtianhong@huawei.com>,
        Hanjun Guo <guohanjun@huawei.com>,
        Libin <huawei.libin@huawei.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Mar 26, 2018 at 2:55 PM, Matthew Wilcox <willy@infradead.org> wrote:
> On Mon, Mar 26, 2018 at 10:01:30PM +0200, Arnd Bergmann wrote:
>> I had suggested a more complete helper function at some point,
>> to take care of all combinations of checking/non-checking, 32/64
>> bit, microsecond/nanosecond, and zeroing/checking the upper 32 bits
>> of nanoseconds before comparing against 1 billion, but Deepa
>> thought that was overkill, so I didn't continue that.
>
> Yeah, that sounds like a nightmare to use ;-)
>
>> For all I can tell, the get_timespec64() helper should almost always
>> include the check, the one exception I know is utimensat() and related
>> functions that may encode the special UTIME_NOW and UTIME_OMIT
>> constants in the nanoseconds.
>
> So do you endorse the get_valid_timespec64() patch I posted up-thread?
> We can't just make get_timespec64 return an errno directly because it'll
> require changing all the users.

I missed this thread earlier.

I had leaned away from this idea before, because of the special cases
which don't need it. I was also trying to keep the syntax close to
copy_from_user(), which is what was there before.

We could probably just change all the
get_timespec64()/compat_get_timespec64() to do the check using a
simple coccinelle script.
I can own this.

But, this would not be needed if Arnd is posting the other helper function.
Arnd, let me know what you prefer here.

-Deepa