From 671a8f877af9c67872648e77e6cf98f32ec8eb68 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Wed, 18 Apr 2018 14:36:24 +0530 Subject: [PATCH] sctp: do not peel off an assoc from one netns to another one Now when peeling off an association to the sock in another netns, all transports in this assoc are not to be rehashed and keep use the old key in hashtable. As a transport uses sk->net as the hash key to insert into hashtable, it would miss removing these transports from hashtable due to the new netns when closing the sock and all transports are being freeed, then later an use-after-free issue could be caused when looking up an asoc and dereferencing those transports. This is a very old issue since very beginning, ChunYu found it with syzkaller fuzz testing with this series: socket$inet6_sctp() bind$inet6() sendto$inet6() unshare(0x40000000) getsockopt$inet_sctp6_SCTP_GET_ASSOC_ID_LIST() getsockopt$inet_sctp6_SCTP_SOCKOPT_PEELOFF() This patch is to block this call when peeling one assoc off from one netns to another one, so that the netns of all transport would not go out-sync with the key in hashtable. Note that this patch didn't fix it by rehashing transports, as it's difficult to handle the situation when the tuple is already in use in the new netns. Besides, no one would like to peel off one assoc to another netns, considering ipaddrs, ifaces, etc. are usually different. Change-Id: Id4da5f2b3347ef35a57ac893868cfa593cf3abfd Reported-by: ChunYu Wang Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller Git-commit: df80cd9b28b9ebaa284a41df611dbf3a2d05ca74 Git-repo: https://android.googlesource.com/kernel/common Signed-off-by: Srinivasa Rao Kuppala --- net/sctp/socket.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 5bb3010aa042..997c266039cf 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4304,6 +4304,10 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) struct sctp_af *af; int err = 0; + /* Do not peel off from one netns to another one. */ + if (!net_eq(current->nsproxy->net_ns, sock_net(sk))) + return -EINVAL; + if (!asoc) return -EINVAL;