From dae399d7fdee84d8f5227a9711d95bb4e9a05d4e Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 31 Oct 2016 20:32:33 +0800 Subject: [PATCH] sctp: hold transport instead of assoc when lookup assoc in rx path Prior to this patch, in rx path, before calling lock_sock, it needed to hold assoc when got it by __sctp_lookup_association, in case other place would free/put assoc. But in __sctp_lookup_association, it lookup and hold transport, then got assoc by transport->assoc, then hold assoc and put transport. It means it didn't hold transport, yet it was returned and later on directly assigned to chunk->transport. Without the protection of sock lock, the transport may be freed/put by other places, which would cause a use-after-free issue. This patch is to fix this issue by holding transport instead of assoc. As holding transport can make sure to access assoc is also safe, and actually it looks up assoc by searching transport rhashtable, to hold transport here makes more sense. Note that the function will be renamed later on on another patch. Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- include/net/sctp/sctp.h | 2 +- net/sctp/input.c | 32 ++++++++++++++++---------------- net/sctp/ipv6.c | 2 +- 3 files changed, 18 insertions(+), 18 deletions(-) diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index 87a7f42e7639..31acc3f4f132 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -152,7 +152,7 @@ void sctp_unhash_endpoint(struct sctp_endpoint *); struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *, struct sctphdr *, struct sctp_association **, struct sctp_transport **); -void sctp_err_finish(struct sock *, struct sctp_association *); +void sctp_err_finish(struct sock *, struct sctp_transport *); void sctp_icmp_frag_needed(struct sock *, struct sctp_association *, struct sctp_transport *t, __u32 pmtu); void sctp_icmp_redirect(struct sock *, struct sctp_transport *, diff --git a/net/sctp/input.c b/net/sctp/input.c index 8e0bc58eec20..a01a56ec8b8c 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -181,9 +181,10 @@ int sctp_rcv(struct sk_buff *skb) * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB */ if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) { - if (asoc) { - sctp_association_put(asoc); + if (transport) { + sctp_transport_put(transport); asoc = NULL; + transport = NULL; } else { sctp_endpoint_put(ep); ep = NULL; @@ -269,8 +270,8 @@ int sctp_rcv(struct sk_buff *skb) bh_unlock_sock(sk); /* Release the asoc/ep ref we took in the lookup calls. */ - if (asoc) - sctp_association_put(asoc); + if (transport) + sctp_transport_put(transport); else sctp_endpoint_put(ep); @@ -283,8 +284,8 @@ discard_it: discard_release: /* Release the asoc/ep ref we took in the lookup calls. */ - if (asoc) - sctp_association_put(asoc); + if (transport) + sctp_transport_put(transport); else sctp_endpoint_put(ep); @@ -300,6 +301,7 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) { struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; struct sctp_inq *inqueue = &chunk->rcvr->inqueue; + struct sctp_transport *t = chunk->transport; struct sctp_ep_common *rcvr = NULL; int backloged = 0; @@ -351,7 +353,7 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) done: /* Release the refs we took in sctp_add_backlog */ if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) - sctp_association_put(sctp_assoc(rcvr)); + sctp_transport_put(t); else if (SCTP_EP_TYPE_SOCKET == rcvr->type) sctp_endpoint_put(sctp_ep(rcvr)); else @@ -363,6 +365,7 @@ done: static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) { struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; + struct sctp_transport *t = chunk->transport; struct sctp_ep_common *rcvr = chunk->rcvr; int ret; @@ -373,7 +376,7 @@ static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) * from us */ if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) - sctp_association_hold(sctp_assoc(rcvr)); + sctp_transport_hold(t); else if (SCTP_EP_TYPE_SOCKET == rcvr->type) sctp_endpoint_hold(sctp_ep(rcvr)); else @@ -537,15 +540,15 @@ struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, return sk; out: - sctp_association_put(asoc); + sctp_transport_put(transport); return NULL; } /* Common cleanup code for icmp/icmpv6 error handler. */ -void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) +void sctp_err_finish(struct sock *sk, struct sctp_transport *t) { bh_unlock_sock(sk); - sctp_association_put(asoc); + sctp_transport_put(t); } /* @@ -641,7 +644,7 @@ void sctp_v4_err(struct sk_buff *skb, __u32 info) } out_unlock: - sctp_err_finish(sk, asoc); + sctp_err_finish(sk, transport); } /* @@ -952,11 +955,8 @@ static struct sctp_association *__sctp_lookup_association( goto out; asoc = t->asoc; - sctp_association_hold(asoc); *pt = t; - sctp_transport_put(t); - out: return asoc; } @@ -986,7 +986,7 @@ int sctp_has_association(struct net *net, struct sctp_transport *transport; if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) { - sctp_association_put(asoc); + sctp_transport_put(transport); return 1; } diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c index f473779e8b1c..176af3080a2b 100644 --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -198,7 +198,7 @@ static void sctp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, } out_unlock: - sctp_err_finish(sk, asoc); + sctp_err_finish(sk, transport); out: if (likely(idev != NULL)) in6_dev_put(idev); -- 2.20.1