From bd891f40f04f8b96d9148ff8a5d538b60171409c Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Tue, 25 Oct 2016 14:27:39 -0200 Subject: [PATCH] sctp: validate chunk len before actually using it [ Upstream commit bf911e985d6bbaa328c20c3e05f4eb03de11fdd6 ] 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 Tested-by: Andrey Konovalov Signed-off-by: Marcelo Ricardo Leitner Reviewed-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- 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 22c2bf367d7e..29c7c43de108 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -3426,6 +3426,12 @@ 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) + WORD_ROUND(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. */ @@ -3457,12 +3463,6 @@ sctp_disposition_t sctp_sf_ootb(struct net *net, } } - /* Report violation if chunk len overflows */ - ch_end = ((__u8 *)ch) + WORD_ROUND(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)); -- 2.34.1