[PATCH net] ipv6: sctp: clone options to avoid use after free
From: Eric Dumazet <hidden>
Date: 2015-12-09 15:25:15
Also in:
linux-sctp, lkml
Subsystem:
networking [general], sctp protocol, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Marcelo Ricardo Leitner, Xin Long, Linus Torvalds
From: Eric Dumazet <edumazet@google.com> SCTP is lacking proper np->opt cloning at accept() time. TCP and DCCP use ipv6_dup_options() helper, do the same in SCTP. We might later factorize this code in a common helper to avoid future mistakes. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/sctp/ipv6.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index d28c0b4c9128..ec529121f38a 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c@@ -641,6 +641,7 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk, struct sock *newsk; struct ipv6_pinfo *newnp, *np = inet6_sk(sk); struct sctp6_sock *newsctp6sk; + struct ipv6_txoptions *opt; newsk = sk_alloc(sock_net(sk), PF_INET6, GFP_KERNEL, sk->sk_prot, 0); if (!newsk)
@@ -660,6 +661,13 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk, memcpy(newnp, np, sizeof(struct ipv6_pinfo)); + rcu_read_lock(); + opt = rcu_dereference(np->opt); + if (opt) + opt = ipv6_dup_options(newsk, opt); + RCU_INIT_POINTER(newnp->opt, opt); + rcu_read_unlock(); + /* Initialize sk's sport, dport, rcv_saddr and daddr for getsockname() * and getpeername(). */