runtime: detect errors in DuplicateHandle

These functions rely on DuplicateHandle succeeding, but they don't check
the return value, which might be masking subtle bugs that cause other
problems down the line.

Updates golang#43720.

Change-Id: I77f0e6645affa534777ffc173144a52e4afa5f81
Reviewed-on: https://go-review.googlesource.com/c/go/+/284135
Run-TryBot: Jason A. Donenfeld <[email protected]>
Reviewed-by: Alex Brainman <[email protected]>
Reviewed-by: Austin Clements <[email protected]>
Trust: Alex Brainman <[email protected]>
Trust: Jason A. Donenfeld <[email protected]>

src/runtime/os_windows.go

@@ -893,7 +893,10 @@ func sigblock(exiting bool) {
 // Called on the new thread, cannot allocate memory.
 func minit() {
 	var thandle uintptr
-	stdcall7(_DuplicateHandle, currentProcess, currentThread, currentProcess, uintptr(unsafe.Pointer(&thandle)), 0, 0, _DUPLICATE_SAME_ACCESS)
+	if stdcall7(_DuplicateHandle, currentProcess, currentThread, currentProcess, uintptr(unsafe.Pointer(&thandle)), 0, 0, _DUPLICATE_SAME_ACCESS) == 0 {
+		print("runtime.minit: duplicatehandle failed; errno=", getlasterror(), "\n")
+		throw("runtime.minit: duplicatehandle failed")
+	}
 
 	// Configure usleep timer, if possible.
 	var timer uintptr
@@ -1134,8 +1137,12 @@ func profileloop1(param uintptr) uint32 {
 			}
 			// Acquire our own handle to the thread.
 			var thread uintptr
-			stdcall7(_DuplicateHandle, currentProcess, mp.thread, currentProcess, uintptr(unsafe.Pointer(&thread)), 0, 0, _DUPLICATE_SAME_ACCESS)
+			if stdcall7(_DuplicateHandle, currentProcess, mp.thread, currentProcess, uintptr(unsafe.Pointer(&thread)), 0, 0, _DUPLICATE_SAME_ACCESS) == 0 {
+				print("runtime.profileloop1: duplicatehandle failed; errno=", getlasterror(), "\n")
+				throw("runtime.profileloop1: duplicatehandle failed")
+			}
 			unlock(&mp.threadLock)
+
 			// mp may exit between the DuplicateHandle
 			// above and the SuspendThread. The handle
 			// will remain valid, but SuspendThread may
@@ -1214,7 +1221,10 @@ func preemptM(mp *m) {
 		return
 	}
 	var thread uintptr
-	stdcall7(_DuplicateHandle, currentProcess, mp.thread, currentProcess, uintptr(unsafe.Pointer(&thread)), 0, 0, _DUPLICATE_SAME_ACCESS)
+	if stdcall7(_DuplicateHandle, currentProcess, mp.thread, currentProcess, uintptr(unsafe.Pointer(&thread)), 0, 0, _DUPLICATE_SAME_ACCESS) == 0 {
+		print("runtime.preemptM: duplicatehandle failed; errno=", getlasterror(), "\n")
+		throw("runtime.preemptM: duplicatehandle failed")
+	}
 	unlock(&mp.threadLock)
 
 	// Prepare thread context buffer. This must be aligned to 16 bytes.