Re: [RESEND v4 2/6] remoteproc: debugfs: Add ability to boot remote processor using debugfs

From: Bjorn Andersson <bjorn@kryo.se>
To: Lee Jones <lee.jones@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Ohad Ben-Cohen <ohad@wizery.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	kernel@stlinux.com, Nathan Lynch <Nathan_Lynch@mentor.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	ludovic.barre@st.com, Maxime Coquelin <maxime.coquelin@st.com>
Subject: Re: [RESEND v4 2/6] remoteproc: debugfs: Add ability to boot remote processor using debugfs
Date: Mon, 28 Dec 2015 10:38:04 -0800	[thread overview]
Message-ID: <CAJAp7OhvwxkS5WkvBgd0ncBRMRCijnU2LggY8oyJ5sHg+5aohQ@mail.gmail.com> (raw)
In-Reply-To: <20151204082427.GC26902@x1>

On Fri, Dec 4, 2015 at 12:24 AM, Lee Jones <lee.jones@linaro.org> wrote:
> On Thu, 03 Dec 2015, Arnd Bergmann wrote:
>
>> On Thursday 03 December 2015 17:28:30 Lee Jones wrote:
>> > >
>> > > Ah, interesting. I haven't tried myself, and just tried to read the
>> > > code. Maybe glibc already catches zero-length writes before it gets
>> > > into the kernel, or I just missed the part of the syscall that checks
>> > > for this.
>> >
>> > Glibc is responsible indeed:
>> >
>> >   http://osxr.org/glibc/source/io/write.c
>>
>> Ok, so an attacker can force the stack overflow by calling
>> syscall(__NR_write, fd, p, 0) if that has any potential value,
>> but normal users won't hit this case.
>
> Right.  I have fixed the issue (and another one I found) anyway, if
> only to rid the GCC warning.
>

Sorry, but I'm unable to find a new version of this patch, did I miss
it or could you resend it?

Also, as I looked at this again, we should probably return an error if
count >= sizeof(buf) rather than just acknowledging the input (same in
the other debugfs write function in this file).

Regards,
Bjorn