On 08/24/2015 06:07 AM, Xin Long wrote:
> in sctp_process_asconf(), we get address parameter from the beginning of the
> addip params. but we never check if it's really there. if the addr param is
> not
> there, it still can pass sctp_verify_asconf(), then to be handled by
> sctp_process_asconf(), it will not be safe.
>
> so add a code in sctp_verify_asconf() to check the address parameter is in the
> beginning, or return false to send abort.
>
> Signed-off-by: Xin Long <[email protected]>
> ---
> net/sctp/sm_make_chunk.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index 0ee5ca7..a2a72d5 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -3122,6 +3122,14 @@ bool sctp_verify_asconf(const struct sctp_association
> *asoc,
> union sctp_params param;
> bool addr_param_seen = false;
>
> + if(addr_param_needed){
> + /* Ensure the address parameter is in the beginning */
> + param.v = chunk->skb->data + sizeof(sctp_addiphdr_t);
> + if (param.p->type != SCTP_PARAM_IPV4_ADDRESS &&
> + param.p->type != SCTP_PARAM_IPV6_ADDRESS)
> + return false;
> + }
> +
Sorry, you can't do that directly without a lot more checks. The parameer
may be only only partial, or may not be there at all. You'd end up looking
at wrong mememory.
A better way would be to set the addr_param_seen only when looking at
the first parameter (addip_hdr.params).
-vlad
> sctp_walk_params(param, addip, addip_hdr.params) {
> size_t length = ntohs(param.p->length);
>
>
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