From 97f54575ff57da3f93f95006802a7892450c1898 Mon Sep 17 00:00:00 2001 From: Davide Caratti Date: Thu, 25 May 2017 19:14:56 +0200 Subject: [PATCH] sctp: fix ICMP processing if skb is non-linear [ Upstream commit 804ec7ebe8ea003999ca8d1bfc499edc6a9e07df ] sometimes ICMP replies to INIT chunks are ignored by the client, even if the encapsulated SCTP headers match an open socket. This happens when the ICMP packet is carried by a paged skb: use skb_header_pointer() to read packet contents beyond the SCTP header, so that chunk header and initiate tag are validated correctly. v2: - don't use skb_header_pointer() to read the transport header, since icmp_socket_deliver() already puts these 8 bytes in the linear area. - change commit message to make specific reference to INIT chunks. Signed-off-by: Davide Caratti Acked-by: Marcelo Ricardo Leitner Acked-by: Vlad Yasevich Reviewed-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sctp/input.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/net/sctp/input.c b/net/sctp/input.c index b6493b3f11a9..2d7859c03fd2 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -472,15 +472,14 @@ struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, struct sctp_association **app, struct sctp_transport **tpp) { + struct sctp_init_chunk *chunkhdr, _chunkhdr; union sctp_addr saddr; union sctp_addr daddr; struct sctp_af *af; struct sock *sk = NULL; struct sctp_association *asoc; struct sctp_transport *transport = NULL; - struct sctp_init_chunk *chunkhdr; __u32 vtag = ntohl(sctphdr->vtag); - int len = skb->len - ((void *)sctphdr - (void *)skb->data); *app = NULL; *tpp = NULL; @@ -515,13 +514,16 @@ struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, * discard the packet. */ if (vtag == 0) { - chunkhdr = (void *)sctphdr + sizeof(struct sctphdr); - if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) - + sizeof(__be32) || + /* chunk header + first 4 octects of init header */ + chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) + + sizeof(struct sctphdr), + sizeof(struct sctp_chunkhdr) + + sizeof(__be32), &_chunkhdr); + if (!chunkhdr || chunkhdr->chunk_hdr.type != SCTP_CID_INIT || - ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { + ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) goto out; - } + } else if (vtag != asoc->c.peer_vtag) { goto out; } -- 2.20.1