Ack: [Lucid][CVE 2/2] sctp: Use correct sideffect command in duplicate cookie handling

[Brad Figg]

On 08/01/2013 02:32 PM, Luis Henriques wrote:
> From: Vlad Yasevich <vyasevich at gmail.com>
>
> CVE-2013-2206
>
> BugLink: http://bugs.launchpad.net/bugs/1194445
>
> When SCTP is done processing a duplicate cookie chunk, it tries
> to delete a newly created association.  For that, it has to set
> the right association for the side-effect processing to work.
> However, when it uses the SCTP_CMD_NEW_ASOC command, that performs
> more work then really needed (like hashing the associationa and
> assigning it an id) and there is no point to do that only to
> delete the association as a next step.  In fact, it also creates
> an impossible condition where an association may be found by
> the getsockopt() call, and that association is empty.  This
> causes a crash in some sctp getsockopts.
>
> The solution is rather simple.  We simply use SCTP_CMD_SET_ASOC
> command that doesn't have all the overhead and does exactly
> what we need.
>
> Reported-by: Karl Heiss <kheiss at gmail.com>
> Tested-by: Karl Heiss <kheiss at gmail.com>
> CC: Neil Horman <nhorman at tuxdriver.com>
> Signed-off-by: Vlad Yasevich <vyasevich at gmail.com>
> Acked-by: Neil Horman <nhorman at tuxdriver.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit f2815633504b442ca0b0605c16bf3d88a3a0fcea)
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>   net/sctp/sm_statefuns.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 9e4e846..486df56 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -2045,7 +2045,7 @@ sctp_disposition_t sctp_sf_do_5_2_4_dupcook(const struct sctp_endpoint *ep,
>   	}
>
>   	/* Delete the tempory new association. */
> -	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
> +	sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC, SCTP_ASOC(new_asoc));
>   	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
>
>   	/* Restore association pointer to provide SCTP command interpeter
>


-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com