1 files changed, 94 insertions, 0 deletions
diff --git a/build/win32/crashinject.cpp b/build/win32/crashinject.cpp
new file mode 100644
index 0000000000..076e5a12a2
--- /dev/null
+++ b/build/win32/crashinject.cpp
@@ -0,0 +1,94 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Given a PID, this program attempts to inject a DLL into the process
+ * with that PID. The DLL it attempts to inject, "crashinjectdll.dll",
+ * must exist alongside this exe. The DLL will then crash the process.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <windows.h>
+
+int main(int argc, char** argv) {
+  if (argc != 2) {
+    fprintf(stderr, "Usage: crashinject <PID>\n");
+    return 1;
+  }
+
+  int pid = atoi(argv[1]);
+  if (pid <= 0) {
+    fprintf(stderr, "Usage: crashinject <PID>\n");
+    return 1;
+  }
+
+  // find our DLL to inject
+  wchar_t filename[_MAX_PATH];
+  if (GetModuleFileNameW(nullptr, filename,
+                         sizeof(filename) / sizeof(wchar_t)) == 0)
+    return 1;
+
+  wchar_t* slash = wcsrchr(filename, L'\\');
+  if (slash == nullptr) return 1;
+
+  slash++;
+  wcscpy(slash, L"crashinjectdll.dll");
+
+  // now find our target process
+  HANDLE targetProc =
+      OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_WRITE |
+                      PROCESS_CREATE_THREAD | PROCESS_QUERY_INFORMATION,
+                  FALSE, pid);
+  if (targetProc == nullptr) {
+    fprintf(stderr, "Error %lu opening target process\n", GetLastError());
+    return 1;
+  }
+
+  /*
+   * This is sort of insane, but we're implementing a technique described here:
+   * http://www.codeproject.com/KB/threads/winspy.aspx#section_2
+   *
+   * The gist is to use CreateRemoteThread to create a thread in the other
+   * process, but cheat and make the thread function kernel32!LoadLibrary,
+   * so that the only remote data we have to pass to the other process
+   * is the path to the library we want to load. The library we're loading
+   * will then do its dirty work inside the other process.
+   */
+  HMODULE hKernel32 = GetModuleHandleW(L"Kernel32");
+  // allocate some memory to hold the path in the remote process
+  void* pLibRemote = VirtualAllocEx(targetProc, nullptr, sizeof(filename),
+                                    MEM_COMMIT, PAGE_READWRITE);
+  if (pLibRemote == nullptr) {
+    fprintf(stderr, "Error %lu in VirtualAllocEx\n", GetLastError());
+    CloseHandle(targetProc);
+    return 1;
+  }
+
+  if (!WriteProcessMemory(targetProc, pLibRemote, (void*)filename,
+                          sizeof(filename), nullptr)) {
+    fprintf(stderr, "Error %lu in WriteProcessMemory\n", GetLastError());
+    VirtualFreeEx(targetProc, pLibRemote, sizeof(filename), MEM_RELEASE);
+    CloseHandle(targetProc);
+    return 1;
+  }
+  // Now create a thread in the target process that will load our DLL
+  HANDLE hThread = CreateRemoteThread(
+      targetProc, nullptr, 0,
+      (LPTHREAD_START_ROUTINE)GetProcAddress(hKernel32, "LoadLibraryW"),
+      pLibRemote, 0, nullptr);
+  if (hThread == nullptr) {
+    fprintf(stderr, "Error %lu in CreateRemoteThread\n", GetLastError());
+    VirtualFreeEx(targetProc, pLibRemote, sizeof(filename), MEM_RELEASE);
+    CloseHandle(targetProc);
+    return 1;
+  }
+  WaitForSingleObject(hThread, INFINITE);
+  // Cleanup, not that it's going to matter at this point
+  CloseHandle(hThread);
+  VirtualFreeEx(targetProc, pLibRemote, sizeof(filename), MEM_RELEASE);
+  CloseHandle(targetProc);
+
+  return 0;
+}