From: Witold Kręcicki <wpk@culm.net>
Date: Fri, 15 Feb 2019 10:28:58 +0000 (+0100)
Subject: Fix a race in socket code when internal_{accept, send, receive} is called
X-Git-Tag: v9.15.0~120^2~1
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=b57a38ae433d2bc7bc8c1de70c7d5c47eaa76ccb;p=thirdparty%2Fbind9.git

Fix a race in socket code when internal_{accept, send, receive} is called
from event loop on an socket and, in the meantime, someone has closed this
socket.
---

diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 4a3365cb474..00ea6a27cff 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -2816,6 +2816,11 @@ internal_accept(isc__socket_t *sock) {
 	INSIST(VALID_SOCKET(sock));
 
 	LOCK(&sock->lock);
+	if (sock->fd < 0) {
+		/* Socket is gone */
+		UNLOCK(&sock->lock);
+		return;
+	}
 	socket_log(sock, NULL, TRACE,
 		   "internal_accept called, locked socket");
 
@@ -3051,6 +3056,11 @@ internal_recv(isc__socket_t *sock) {
 	INSIST(VALID_SOCKET(sock));
 
 	LOCK(&sock->lock);
+	if (sock->fd < 0) {
+		/* Socket is gone */
+		UNLOCK(&sock->lock);
+		return;
+	}
 	dev = ISC_LIST_HEAD(sock->recv_list);
 	if (dev == NULL) {
 		goto finish;
@@ -3105,6 +3115,11 @@ internal_send(isc__socket_t *sock) {
 	INSIST(VALID_SOCKET(sock));
 
 	LOCK(&sock->lock);
+	if (sock->fd < 0) {
+		/* Socket is gone */
+		UNLOCK(&sock->lock);
+		return;
+	}
 	dev = ISC_LIST_HEAD(sock->send_list);
 	if (dev == NULL) {
 		goto finish;