linux-kernel - Re: [PATCH] Remove hardcoded static string length

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Message-ID: <5b1355b8-17f7-49c8-b7b5-3d9ecdb146ce@lunn.ch>
Date:   Wed, 24 May 2023 19:43:11 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     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 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 other end of the socket should not blow up, because that would be
an obvious DOS or buffer overwrite attack vector. So you need to
decide, do you want to expose such issues and see if anything does
actually blow up, or do you want to do a bit more work and correctly
terminate the string when capped?

	Andrew