lkml.org 
[lkml]   [2016]   [Oct]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: net/sctp: slab-out-of-bounds in sctp_sf_ootb
Hi Marcelo,

I can confirm that your patch fixes the issue for me.

Tested-by: Andrey Konovalov <andreyknvl@google.com>

On Mon, Oct 24, 2016 at 9:44 PM, Marcelo Ricardo Leitner
<marcelo.leitner@gmail.com> wrote:
> Hi Andrey,
>
> On Mon, Oct 24, 2016 at 05:30:04PM +0200, Andrey Konovalov wrote:
>> The problem is that sctp_walk_errors walks the chunk before its length
>> is checked for overflow.
>
> Exactly. The check is done too late, for the 2nd and subsequent chunks
> only.
> Please try the following patch, thanks. Note: not even compile tested.
>
> ---8<---
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 026e3bca4a94..8ec20a64a3f8 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));
>

\
 
 \ /
  Last update: 2016-10-25 14:24    [W:0.053 / U:0.956 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site