From 86fdb3448cc1ffe0e9f55380f1410f1d12c35f95 Mon Sep 17 00:00:00 2001
From: Xin Long <lucien.xin@gmail.com>
Date: Sat, 17 Jun 2017 16:10:27 +0800
Subject: [PATCH] sctp: ensure ep is not destroyed before doing the dump
Now before dumping a sock in sctp_diag, it only holds the sock while
the ep may be already destroyed. It can cause a use-after-free panic
when accessing ep->asocs.
This patch is to set sctp_sk(sk)->ep NULL in sctp_endpoint_destroy,
and check if this ep is already destroyed before dumping this ep.
Suggested-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdrver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/sctp/endpointola.c | 1 +
net/sctp/sctp_diag.c | 5 +++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c
index 8c589230794f9..3dcd0ecf3d99f 100644
--- a/net/sctp/endpointola.c
+++ b/net/sctp/endpointola.c
@@ -275,6 +275,7 @@ static void sctp_endpoint_destroy(struct sctp_endpoint *ep)
if (sctp_sk(sk)->bind_hash)
sctp_put_port(sk);
+ sctp_sk(sk)->ep = NULL;
sock_put(sk);
}
diff --git a/net/sctp/sctp_diag.c b/net/sctp/sctp_diag.c
index 048954eee984f..9a647214a91eb 100644
--- a/net/sctp/sctp_diag.c
+++ b/net/sctp/sctp_diag.c
@@ -278,7 +278,6 @@ static int sctp_tsp_dump_one(struct sctp_transport *tsp, void *p)
static int sctp_sock_dump(struct sock *sk, void *p)
{
- struct sctp_endpoint *ep = sctp_sk(sk)->ep;
struct sctp_comm_param *commp = p;
struct sk_buff *skb = commp->skb;
struct netlink_callback *cb = commp->cb;
@@ -287,7 +286,9 @@ static int sctp_sock_dump(struct sock *sk, void *p)
int err = 0;
lock_sock(sk);
- list_for_each_entry(assoc, &ep->asocs, asocs) {
+ if (!sctp_sk(sk)->ep)
+ goto release;
+ list_for_each_entry(assoc, &sctp_sk(sk)->ep->asocs, asocs) {
if (cb->args[4] < cb->args[1])
goto next;
--
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