netdev - Re: [Security] [SECURITY] CAN info leak/minor heap overflow

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Message-ID: <AANLkTi=EcAQ0u_wYAnVkvV_Ve9in4z2Es5h1pBbyMeXe@mail.gmail.com>
Date:	Tue, 2 Nov 2010 15:57:53 -0400
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dan Rosenberg <drosenberg@...curity.com>
Cc:	Oliver Hartkopp <socketcan@...tkopp.net>, netdev@...r.kernel.org,
	security@...nel.org
Subject: Re: [Security] [SECURITY] CAN info leak/minor heap overflow

On Tue, Nov 2, 2010 at 3:53 PM, Dan Rosenberg <drosenberg@...curity.com> wrote:
>
>> Why is this bad? Can the addresses of CAN-BCM sock structs be used for
>> anything from userspace?
>>
>> For me they are just intented to be unique numbers ...
>>
>
> This is a bad idea because it makes exploiting other kernel
> vulnerabilities easier.  Exposing the address of an object in a slab
> cache, especially an object that unprivileged users have some level of
> control of, is just an invitation to use that structure when writing
> exploits, for heap overflows or otherwise.

Indeed. At the very least, hash them and truncate them with some
secret per-boot value or something. Even better, use something like a
socket number so that maybe they can be associated with
/proc/<xyz>/fd/<x> or other system info if somebody were to care.

             Linus
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