linux-kernel - Re: [PATCH] pktgen: Remove a dangerous debug print.

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Message-ID: <20101027194905.GQ16803@ksplice.com>
Date:	Wed, 27 Oct 2010 15:49:05 -0400
From:	Nelson Elhage <nelhage@...lice.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>, robert.olsson@....uu.se,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	eugene@...hat.com
Subject: Re: [PATCH] pktgen: Remove a dangerous debug print.

I tested this and was able to oops both amd64 and i386 test machines with 8k
writes to the pktgen file. I haven't investigated whether that's because there's
no PAGE_SIZE limit, or because one page ends up being enough to cause a problem
on all my test machines.

- Nelson

On Wed, Oct 27, 2010 at 09:41:39PM +0200, Eric Dumazet wrote:
> Le mercredi 27 octobre 2010 à 15:28 -0400, Nelson Elhage a écrit :
> > How would you feel about limiting the debug print to at most, say, 512 or 1024
> > bytes? Even if it's only accessible to root by default, I don't a userspace
> > program should be able to accidentally corrupt the kernel stack by writing too
> > many bytes to a file in /proc.
> 
> Arent /proc writes limited to PAGE_SIZE anyway ?
> 
> On x86 at least, you cannot corrupt kernel stack, since its bigger than
> PAGE_SIZE.
> 
> I agree pktgen code is a bit ugly and needs a cleanup, but who
> cares ? :)
> 
> 
> 
> 
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