From 86fdb3448cc1ffe0e9f55380f1410f1d12c35f95 Mon Sep 17 00:00:00 2001 From: Xin Long 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 Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller --- 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 8c589230794f..3dcd0ecf3d99 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 048954eee984..9a647214a91e 100644 --- a/net/sctp/sctp_diag.c +++ b/net/sctp/sctp_diag.c @@ -278,7 +278,6 @@ out: 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; -- 2.20.1