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

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Message-ID: <CAJAp7OhvwxkS5WkvBgd0ncBRMRCijnU2LggY8oyJ5sHg+5aohQ@mail.gmail.com>
Date:	Mon, 28 Dec 2015 10:38:04 -0800
From:	Bjorn Andersson <bjorn@...o.se>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Ohad Ben-Cohen <ohad@...ery.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Florian Fainelli <f.fainelli@...il.com>, kernel@...inux.com,
	Nathan Lynch <Nathan_Lynch@...tor.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	ludovic.barre@...com, Maxime Coquelin <maxime.coquelin@...com>
Subject: Re: [RESEND v4 2/6] remoteproc: debugfs: Add ability to boot remote
 processor using debugfs

On Fri, Dec 4, 2015 at 12:24 AM, Lee Jones <lee.jones@...aro.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
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