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

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Message-ID: <CAJAp7OgF_2MNyuK9aKi9BRpq9B918MKijrjByDeZ_iZZbkR7iw@mail.gmail.com>
Date:	Thu, 3 Dec 2015 13:22:50 -0800
From:	Bjorn Andersson <bjorn@...o.se>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Lee Jones <lee.jones@...aro.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 Thu, Dec 3, 2015 at 1:12 PM, Arnd Bergmann <arnd@...db.de> 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.
>

It seems glibc might be the only libc implementation with this protection.

Regards,
Bjorn
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