netdev - Re: [PATCH] Remove hardcoded static string length

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Message-ID: <76cb5084-a2aa-6ccd-b531-6338f6673f51@auristor.com>
Date: Sat, 27 May 2023 11:08:33 -0400
From: Jeffrey E Altman <jaltman@...istor.com>
To: Andrew Lunn <andrew@...n.ch>, Kenny Ho <y2kenny@...il.com>
Cc: Marc Dionne <marc.dionne@...istor.com>, Kenny Ho <Kenny.Ho@....com>,
 David Howells <dhowells@...hat.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 linux-afs@...ts.infradead.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Remove hardcoded static string length

On 5/24/2023 1:43 PM, Andrew Lunn wrote:
> On Wed, May 24, 2023 at 01:02:36PM -0400, Kenny Ho wrote:
>> On Wed, May 24, 2023 at 12:02 PM Andrew Lunn <andrew@...n.ch> wrote:
>>> So the compiler warning/error needs to be fixed a different want.
>> Understood. Would caping the length at iov_len with a ternary be 
>> sufficient?
> The quoted text said 'string'. It is not clear if that means c-string,
> with a trailing \0. If you just cap iov_len you could end up with a
> string which is not terminated.
The expected buffer is a NUL terminated c-string.
> The other end of the socket should not blow up, because that would be
> an obvious DOS or buffer overwrite attack vector.

This is a valid concern because all versions of IBM AFS 3.6 Rx and 
OpenAFS Rx prior to 1.6.23 are susceptible to read beyond the end of 
buffer if either the received data is longer than 65 octets or the 
received data is 65 octets but not NUL terminated.

Jeffrey Altman

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