On Tue, Oct 25, 2016 at 02:27:39PM -0200, Marcelo Ricardo Leitner wrote:
> Andrey Konovalov reported that KASAN detected that SCTP was using a slab
> beyond the boundaries. It was caused because when handling out of the
> blue packets in function sctp_sf_ootb() it was checking the chunk len
> only after already processing the first chunk, validating only for the
> 2nd and subsequent ones.
>
> The fix is to just move the check upwards so it's also validated for the
> 1st chunk.
>
> Reported-by: Andrey Konovalov <[email protected]>
> Tested-by: Andrey Konovalov <[email protected]>
> Signed-off-by: Marcelo Ricardo Leitner <[email protected]>
> ---
>
> Hi. Please consider this to -stable too. Thanks
>
> net/sctp/sm_statefuns.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index
> 026e3bca4a94bd34b418d5e6947f7182c1512358..8ec20a64a3f8055a0c3576627c5ec5dad7e99ca8
> 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -3422,6 +3422,12 @@ sctp_disposition_t sctp_sf_ootb(struct net *net,
> return sctp_sf_violation_chunklen(net, ep, asoc, type,
> arg,
> commands);
>
> + /* Report violation if chunk len overflows */
> + ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
> + if (ch_end > skb_tail_pointer(skb))
> + return sctp_sf_violation_chunklen(net, ep, asoc, type,
> arg,
> + commands);
> +
> /* Now that we know we at least have a chunk header,
> * do things that are type appropriate.
> */
> @@ -3453,12 +3459,6 @@ sctp_disposition_t sctp_sf_ootb(struct net *net,
> }
> }
>
> - /* Report violation if chunk len overflows */
> - ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
> - if (ch_end > skb_tail_pointer(skb))
> - return sctp_sf_violation_chunklen(net, ep, asoc, type,
> arg,
> - commands);
> -
> ch = (sctp_chunkhdr_t *) ch_end;
> } while (ch_end < skb_tail_pointer(skb));
>
> --
> 2.7.4
>
> --
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>
Acked-by: Neil Horman <[email protected]>
