From 804ec7ebe8ea003999ca8d1bfc499edc6a9e07df Mon Sep 17 00:00:00 2001 From: Davide Caratti Date: Thu, 25 May 2017 19:14:56 +0200 Subject: sctp: fix ICMP processing if skb is non-linear 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 --- net/sctp/input.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'net') diff --git a/net/sctp/input.c b/net/sctp/input.c index 0e06a278d2a9..ba9ad32fc447 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -473,15 +473,14 @@ 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; @@ -516,13 +515,16 @@ 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; } -- cgit v1.2.3-59-g8ed1b