Fix for panic in endpoint.Close().

When sending a RST on shutdown we need to double check the
state after acquiring the work mutex as the endpoint could
have transitioned out of a connected state from the time
we checked it and we acquired the workMutex.

I added two tests but sadly neither reproduce the panic. I am
going to leave the tests in as they are good to have anyway.

PiperOrigin-RevId: 292393800

2 files changed, 34 insertions, 0 deletions

diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 74bf068ec..7958fd0d7 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -2173,6 +2173,7 @@ cc_library(
         ":socket_test_util",
         "//test/util:test_util",
         "//test/util:thread_util",
+        "@com_google_absl//absl/memory",
         "@com_google_absl//absl/time",
         "@com_google_googletest//:gtest",
     ],
diff --git a/test/syscalls/linux/socket_ip_tcp_generic.cc b/test/syscalls/linux/socket_ip_tcp_generic.cc
index 57ce8e169..27779e47c 100644
--- a/test/syscalls/linux/socket_ip_tcp_generic.cc
+++ b/test/syscalls/linux/socket_ip_tcp_generic.cc
@@ -24,6 +24,7 @@
 #include <sys/un.h>
 
 #include "gtest/gtest.h"
+#include "absl/memory/memory.h"
 #include "absl/time/clock.h"
 #include "absl/time/time.h"
 #include "test/syscalls/linux/socket_test_util.h"
@@ -875,5 +876,37 @@ TEST_P(TCPSocketPairTest, SetTCPUserTimeoutAboveZero) {
   EXPECT_EQ(get, kAbove);
 }
 
+TEST_P(TCPSocketPairTest, TCPResetDuringClose_NoRandomSave) {
+  DisableSave ds;  // Too many syscalls.
+  constexpr int kThreadCount = 1000;
+  std::unique_ptr<ScopedThread> instances[kThreadCount];
+  for (int i = 0; i < kThreadCount; i++) {
+    instances[i] = absl::make_unique<ScopedThread>([&]() {
+      auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
+
+      ScopedThread t([&]() {
+        // Close one end to trigger sending of a FIN.
+        struct pollfd poll_fd = {sockets->second_fd(), POLLIN | POLLHUP, 0};
+        // Wait up to 20 seconds for the data.
+        constexpr int kPollTimeoutMs = 20000;
+        ASSERT_THAT(RetryEINTR(poll)(&poll_fd, 1, kPollTimeoutMs),
+                    SyscallSucceedsWithValue(1));
+        ASSERT_THAT(close(sockets->release_second_fd()), SyscallSucceeds());
+      });
+
+      // Send some data then close.
+      constexpr char kStr[] = "abc";
+      ASSERT_THAT(write(sockets->first_fd(), kStr, 3),
+                  SyscallSucceedsWithValue(3));
+      absl::SleepFor(absl::Milliseconds(10));
+      ASSERT_THAT(close(sockets->release_first_fd()), SyscallSucceeds());
+      t.Join();
+    });
+  }
+  for (int i = 0; i < kThreadCount; i++) {
+    instances[i]->Join();
+  }
+}
+
 }  // namespace testing
 }  // namespace gvisor