linux-kernel - Re: [PATCH] dns_resolver: assure that dns

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Message-ID: <CAHQdGtTtwS_DAXx-nhVjjO3D1wksuV+5br10gX0DheHzWDD+sw@mail.gmail.com>
Date:	Sat, 7 Jun 2014 14:54:56 -0400
From:	Trond Myklebust <trond.myklebust@...marydata.com>
To:	Manuel Schölling <manuel.schoelling@....de>
Cc:	"Miller David S." <davem@...emloft.net>,
	jeffrey.t.kirsher@...el.com,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Linux Kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dns_resolver: assure that dns_query() result is null-terminated

On Sat, Jun 7, 2014 at 1:56 PM, Manuel Schölling
<manuel.schoelling@....de> wrote:
> dns_query() credulously assumes that keys are null-terminated and
> returns a copy of a memory block that is off by one.
> ---
>  net/dns_resolver/dns_query.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
> index e7b6d53..53be635 100644
> --- a/net/dns_resolver/dns_query.c
> +++ b/net/dns_resolver/dns_query.c
> @@ -149,7 +149,9 @@ int dns_query(const char *type, const char *name, size_t namelen,
>         if (!*_result)
>                 goto put;
>
> -       memcpy(*_result, upayload->data, len + 1);
> +       memcpy(*_result, upayload->data, len);
> +       *_result[len+1] = '\0';

Off by one...

> +
>         if (_expiry)
>                 *_expiry = rkey->expiry;
>
> --
> 1.7.10.4
>
> --
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-- 
Trond Myklebust

Linux NFS client maintainer, PrimaryData

trond.myklebust@...marydata.com
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