The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From f9d31c4cf4c11ff10317f038b9c6f7c3bda6cdd4 Mon Sep 17 00:00:00 2001 From: Xin Long lucien.xin@gmail.com Date: Fri, 31 Dec 2021 18:37:37 -0500 Subject: [PATCH] sctp: hold endpoint before calling cb in sctp_transport_lookup_process
The same fix in commit 5ec7d18d1813 ("sctp: use call_rcu to free endpoint") is also needed for dumping one asoc and sock after the lookup.
Fixes: 86fdb3448cc1 ("sctp: ensure ep is not destroyed before doing the dump") Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index d314a180ab93..3ae61ce2eabd 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -112,8 +112,7 @@ struct sctp_transport *sctp_transport_get_next(struct net *net, struct rhashtable_iter *iter); struct sctp_transport *sctp_transport_get_idx(struct net *net, struct rhashtable_iter *iter, int pos); -int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *), - struct net *net, +int sctp_transport_lookup_process(sctp_callback_t cb, struct net *net, const union sctp_addr *laddr, const union sctp_addr *paddr, void *p); int sctp_transport_traverse_process(sctp_callback_t cb, sctp_callback_t cb_done, diff --git a/net/sctp/diag.c b/net/sctp/diag.c index a7d623171501..034e2c74497d 100644 --- a/net/sctp/diag.c +++ b/net/sctp/diag.c @@ -245,48 +245,44 @@ static size_t inet_assoc_attr_size(struct sctp_association *asoc) + 64; }
-static int sctp_tsp_dump_one(struct sctp_transport *tsp, void *p) +static int sctp_sock_dump_one(struct sctp_endpoint *ep, struct sctp_transport *tsp, void *p) { struct sctp_association *assoc = tsp->asoc; - struct sock *sk = tsp->asoc->base.sk; struct sctp_comm_param *commp = p; - struct sk_buff *in_skb = commp->skb; + struct sock *sk = ep->base.sk; const struct inet_diag_req_v2 *req = commp->r; - const struct nlmsghdr *nlh = commp->nlh; - struct net *net = sock_net(in_skb->sk); + struct sk_buff *skb = commp->skb; struct sk_buff *rep; int err;
err = sock_diag_check_cookie(sk, req->id.idiag_cookie); if (err) - goto out; + return err;
- err = -ENOMEM; rep = nlmsg_new(inet_assoc_attr_size(assoc), GFP_KERNEL); if (!rep) - goto out; + return -ENOMEM;
lock_sock(sk); - if (sk != assoc->base.sk) { - release_sock(sk); - sk = assoc->base.sk; - lock_sock(sk); + if (ep != assoc->ep) { + err = -EAGAIN; + goto out; } - err = inet_sctp_diag_fill(sk, assoc, rep, req, - sk_user_ns(NETLINK_CB(in_skb).sk), - NETLINK_CB(in_skb).portid, - nlh->nlmsg_seq, 0, nlh, - commp->net_admin); - release_sock(sk); + + err = inet_sctp_diag_fill(sk, assoc, rep, req, sk_user_ns(NETLINK_CB(skb).sk), + NETLINK_CB(skb).portid, commp->nlh->nlmsg_seq, 0, + commp->nlh, commp->net_admin); if (err < 0) { WARN_ON(err == -EMSGSIZE); - kfree_skb(rep); goto out; } + release_sock(sk);
- err = nlmsg_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid); + return nlmsg_unicast(sock_net(skb->sk)->diag_nlsk, rep, NETLINK_CB(skb).portid);
out: + release_sock(sk); + kfree_skb(rep); return err; }
@@ -429,15 +425,15 @@ static void sctp_diag_get_info(struct sock *sk, struct inet_diag_msg *r, static int sctp_diag_dump_one(struct netlink_callback *cb, const struct inet_diag_req_v2 *req) { - struct sk_buff *in_skb = cb->skb; - struct net *net = sock_net(in_skb->sk); + struct sk_buff *skb = cb->skb; + struct net *net = sock_net(skb->sk); const struct nlmsghdr *nlh = cb->nlh; union sctp_addr laddr, paddr; struct sctp_comm_param commp = { - .skb = in_skb, + .skb = skb, .r = req, .nlh = nlh, - .net_admin = netlink_net_capable(in_skb, CAP_NET_ADMIN), + .net_admin = netlink_net_capable(skb, CAP_NET_ADMIN), };
if (req->sdiag_family == AF_INET) { @@ -460,7 +456,7 @@ static int sctp_diag_dump_one(struct netlink_callback *cb, paddr.v6.sin6_family = AF_INET6; }
- return sctp_transport_lookup_process(sctp_tsp_dump_one, + return sctp_transport_lookup_process(sctp_sock_dump_one, net, &laddr, &paddr, &commp); }
diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ad5028a07b18..da08671a3f80 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -5317,23 +5317,31 @@ int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), } EXPORT_SYMBOL_GPL(sctp_for_each_endpoint);
-int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *), - struct net *net, +int sctp_transport_lookup_process(sctp_callback_t cb, struct net *net, const union sctp_addr *laddr, const union sctp_addr *paddr, void *p) { struct sctp_transport *transport; - int err; + struct sctp_endpoint *ep; + int err = -ENOENT;
rcu_read_lock(); transport = sctp_addrs_lookup_transport(net, laddr, paddr); + if (!transport) { + rcu_read_unlock(); + return err; + } + ep = transport->asoc->ep; + if (!sctp_endpoint_hold(ep)) { /* asoc can be peeled off */ + sctp_transport_put(transport); + rcu_read_unlock(); + return err; + } rcu_read_unlock(); - if (!transport) - return -ENOENT;
- err = cb(transport, p); + err = cb(ep, transport, p); + sctp_endpoint_put(ep); sctp_transport_put(transport); - return err; } EXPORT_SYMBOL_GPL(sctp_transport_lookup_process);