From 2cd206d0fce477d123ab8b7acf19fdf34ca0a7aa Mon Sep 17 00:00:00 2001
From: Paul Holzinger <pholzing@redhat.com>
Date: Tue, 5 Oct 2021 11:13:49 +0200
Subject: libpod: fix race when closing STDIN

There is a race where `conn.Close()` was called before `conn.CloseWrite()`.
In this case `CloseWrite` will fail and an useless error is printed. To
fix this we move the the `CloseWrite()` call to the same goroutine to
remove the race. This ensures that `CloseWrite()` is called before
`Close()` and never afterwards.
Also fixed podman-remote run where the STDIN was never was closed.
This is causing flakes in CI testing.

[NO TESTS NEEDED]

Fixes #11856

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

<MH: Fixed cherry-pick conflicts>

Signed-off-by: Matthew Heon <matthew.heon@pm.me>
---
 libpod/oci_attach_linux.go      | 17 +++++++++--------
 libpod/oci_conmon_exec_linux.go |  7 ++++---
 libpod/oci_conmon_linux.go      |  4 ++++
 3 files changed, 17 insertions(+), 11 deletions(-)

(limited to 'libpod')

diff --git a/libpod/oci_attach_linux.go b/libpod/oci_attach_linux.go
index de435b58a..702628aa8 100644
--- a/libpod/oci_attach_linux.go
+++ b/libpod/oci_attach_linux.go
@@ -84,7 +84,7 @@ func (c *Container) attach(streams *define.AttachStreams, keys string, resize <-
 	if attachRdy != nil {
 		attachRdy <- true
 	}
-	return readStdio(streams, receiveStdoutError, stdinDone)
+	return readStdio(conn, streams, receiveStdoutError, stdinDone)
 }
 
 // Attach to the given container's exec session
@@ -165,7 +165,7 @@ func (c *Container) attachToExec(streams *define.AttachStreams, keys *string, se
 		return err
 	}
 
-	return readStdio(streams, receiveStdoutError, stdinDone)
+	return readStdio(conn, streams, receiveStdoutError, stdinDone)
 }
 
 func processDetachKeys(keys string) ([]byte, error) {
@@ -208,11 +208,6 @@ func setupStdioChannels(streams *define.AttachStreams, conn *net.UnixConn, detac
 		var err error
 		if streams.AttachInput {
 			_, err = utils.CopyDetachable(conn, streams.InputStream, detachKeys)
-			if err == nil {
-				if connErr := conn.CloseWrite(); connErr != nil {
-					logrus.Errorf("unable to close conn: %q", connErr)
-				}
-			}
 		}
 		stdinDone <- err
 	}()
@@ -265,7 +260,7 @@ func redirectResponseToOutputStreams(outputStream, errorStream io.Writer, writeO
 	return err
 }
 
-func readStdio(streams *define.AttachStreams, receiveStdoutError, stdinDone chan error) error {
+func readStdio(conn *net.UnixConn, streams *define.AttachStreams, receiveStdoutError, stdinDone chan error) error {
 	var err error
 	select {
 	case err = <-receiveStdoutError:
@@ -274,6 +269,12 @@ func readStdio(streams *define.AttachStreams, receiveStdoutError, stdinDone chan
 		if err == define.ErrDetach {
 			return err
 		}
+		if err == nil {
+			// copy stdin is done, close it
+			if connErr := conn.CloseWrite(); connErr != nil {
+				logrus.Errorf("Unable to close conn: %v", connErr)
+			}
+		}
 		if streams.AttachOutput || streams.AttachError {
 			return <-receiveStdoutError
 		}
diff --git a/libpod/oci_conmon_exec_linux.go b/libpod/oci_conmon_exec_linux.go
index 5a7677b04..553c91833 100644
--- a/libpod/oci_conmon_exec_linux.go
+++ b/libpod/oci_conmon_exec_linux.go
@@ -609,9 +609,6 @@ func attachExecHTTP(c *Container, sessionID string, r *http.Request, w http.Resp
 			_, err := utils.CopyDetachable(conn, httpBuf, detachKeys)
 			logrus.Debugf("STDIN copy completed")
 			stdinChan <- err
-			if connErr := conn.CloseWrite(); connErr != nil {
-				logrus.Errorf("Unable to close conn: %v", connErr)
-			}
 		}()
 	}
 
@@ -654,6 +651,10 @@ func attachExecHTTP(c *Container, sessionID string, r *http.Request, w http.Resp
 			if err != nil {
 				return err
 			}
+			// copy stdin is done, close it
+			if connErr := conn.CloseWrite(); connErr != nil {
+				logrus.Errorf("Unable to close conn: %v", connErr)
+			}
 		case <-cancel:
 			return nil
 		}
diff --git a/libpod/oci_conmon_linux.go b/libpod/oci_conmon_linux.go
index c2b472f76..58aa3557a 100644
--- a/libpod/oci_conmon_linux.go
+++ b/libpod/oci_conmon_linux.go
@@ -699,6 +699,10 @@ func (r *ConmonOCIRuntime) HTTPAttach(ctr *Container, req *http.Request, w http.
 			if err != nil {
 				return err
 			}
+			// copy stdin is done, close it
+			if connErr := conn.CloseWrite(); connErr != nil {
+				logrus.Errorf("Unable to close conn: %v", connErr)
+			}
 		case <-cancel:
 			return nil
 		}
-- 
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