From dfbc0b0a4cabc6468c82a7665ff655fd4a633dd9 Mon Sep 17 00:00:00 2001
From: Bhasker Hariharan <bhaskerh@google.com>
Date: Tue, 6 Aug 2019 10:59:49 -0700
Subject: Fix for a panic due to writing to a closed accept channel.

This can happen because endpoint.Close() closes the accept channel first and
then drains/resets any accepted but not delivered connections. But there can be
connections that are connected but not delivered to the channel as the channel
was full. But closing the channel can cause these writes to fail with a write to
a closed channel.

The correct solution is to abort any connections in SYN-RCVD state and
drain/abort all completed connections before closing the accept channel.

PiperOrigin-RevId: 261951132
---
 test/syscalls/BUILD                         |  4 +-
 test/syscalls/linux/socket_inet_loopback.cc | 61 +++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)

(limited to 'test')

diff --git a/test/syscalls/BUILD b/test/syscalls/BUILD
index a3e43cad2..aa1e33fb4 100644
--- a/test/syscalls/BUILD
+++ b/test/syscalls/BUILD
@@ -440,7 +440,9 @@ syscall_test(
 )
 
 syscall_test(
-    size = "medium",
+    size = "large",
+    parallel = False,
+    shard_count = 10,
     test = "//test/syscalls/linux:socket_inet_loopback_test",
 )
 
diff --git a/test/syscalls/linux/socket_inet_loopback.cc b/test/syscalls/linux/socket_inet_loopback.cc
index df31d25b5..322ee07ad 100644
--- a/test/syscalls/linux/socket_inet_loopback.cc
+++ b/test/syscalls/linux/socket_inet_loopback.cc
@@ -145,6 +145,67 @@ TEST_P(SocketInetLoopbackTest, TCP) {
   ASSERT_THAT(shutdown(conn_fd.get(), SHUT_RDWR), SyscallSucceeds());
 }
 
+TEST_P(SocketInetLoopbackTest, TCPListenClose) {
+  auto const& param = GetParam();
+
+  TestAddress const& listener = param.listener;
+  TestAddress const& connector = param.connector;
+
+  // Create the listening socket.
+  FileDescriptor listen_fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Socket(listener.family(), SOCK_STREAM, IPPROTO_TCP));
+  sockaddr_storage listen_addr = listener.addr;
+  ASSERT_THAT(bind(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr),
+                   listener.addr_len),
+              SyscallSucceeds());
+  ASSERT_THAT(listen(listen_fd.get(), 1001), SyscallSucceeds());
+
+  // Get the port bound by the listening socket.
+  socklen_t addrlen = listener.addr_len;
+  ASSERT_THAT(getsockname(listen_fd.get(),
+                          reinterpret_cast<sockaddr*>(&listen_addr), &addrlen),
+              SyscallSucceeds());
+  uint16_t const port =
+      ASSERT_NO_ERRNO_AND_VALUE(AddrPort(listener.family(), listen_addr));
+
+  DisableSave ds;  // Too many system calls.
+  sockaddr_storage conn_addr = connector.addr;
+  ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port));
+  constexpr int kFDs = 2048;
+  constexpr int kThreadCount = 4;
+  constexpr int kFDsPerThread = kFDs / kThreadCount;
+  FileDescriptor clients[kFDs];
+  std::unique_ptr<ScopedThread> threads[kThreadCount];
+  for (int i = 0; i < kFDs; i++) {
+    clients[i] = ASSERT_NO_ERRNO_AND_VALUE(
+        Socket(connector.family(), SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP));
+  }
+  for (int i = 0; i < kThreadCount; i++) {
+    threads[i] = absl::make_unique<ScopedThread>([&connector, &conn_addr,
+                                                  &clients, i]() {
+      for (int j = 0; j < kFDsPerThread; j++) {
+        int k = i * kFDsPerThread + j;
+        int ret =
+            connect(clients[k].get(), reinterpret_cast<sockaddr*>(&conn_addr),
+                    connector.addr_len);
+        if (ret != 0) {
+          EXPECT_THAT(ret, SyscallFailsWithErrno(EINPROGRESS));
+        }
+      }
+    });
+  }
+  for (int i = 0; i < kThreadCount; i++) {
+    threads[i]->Join();
+  }
+  for (int i = 0; i < 32; i++) {
+    auto accepted =
+        ASSERT_NO_ERRNO_AND_VALUE(Accept(listen_fd.get(), nullptr, nullptr));
+  }
+  // TODO(b/138400178): Fix cooperative S/R failure when ds.reset() is invoked
+  // before function end.
+  // ds.reset()
+}
+
 TEST_P(SocketInetLoopbackTest, TCPbacklog) {
   auto const& param = GetParam();
 
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