device: wait for and lock ipc operations during close

raggi · zx2c4 · commit b7cd547315be · 2023-06-27T17:43:35.000+02:00
If an IPC operation is in flight while close starts, it is possible for
both processes to deadlock. Prevent this by taking the IPC lock at the
start of close and for the duration.

Signed-off-by: James Tucker &lt;jftucker@gmail.com&gt;
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
diff --git a/device/device.go b/device/device.go
@@ -368,6 +368,8 @@ func (device *Device) RemoveAllPeers() {
 }
 
 func (device *Device) Close() {
+	device.ipcMutex.Lock()
+	defer device.ipcMutex.Unlock()
 	device.state.Lock()
 	defer device.state.Unlock()
 	if device.isClosed() {

Original file line number	Diff line number	Diff line change
`@@ -368,6 +368,8 @@ func (device *Device) RemoveAllPeers() {`
`368`	`368`	`}`
`369`	`369`
`370`	`370`	`func (device *Device) Close() {`
	`371`	`+ device.ipcMutex.Lock()`
	`372`	`+ defer device.ipcMutex.Unlock()`
`371`	`373`	`device.state.Lock()`
`372`	`374`	`defer device.state.Unlock()`
`373`	`375`	`if device.isClosed() {`