fix: add bounds checking for file operations and string lengths

- add assertions for freopen operations in PreInit
- limit string length with kStrlenMaxLength in GFBuffer
- add bounds checking for file read operations
- simplify error handling in ReadFileGFBuffer

Author: saturneric

src/Initialize.cpp

@@ -69,9 +69,9 @@ void PreInit(const GFCxtWPtr &p_ctx) {
   const auto console = app->property("GFShowConsoleOnWindows").toBool();
 
   if (console && AllocConsole()) {
-    freopen("CONOUT$", "w", stdout);
-    freopen("CONOUT$", "w", stderr);
-    freopen("CONIN$", "r", stdin);
+    Q_ASSERT(freopen("CONOUT$", "w", stdout) != nullptr);
+    Q_ASSERT(freopen("CONOUT$", "w", stderr) != nullptr);
+    Q_ASSERT(freopen("CONIN$", "r", stdin) != nullptr);
     setvbuf(stdout, NULL, _IONBF, 0);
 
     qInstallMessageHandler([](QtMsgType type, const QMessageLogContext &context,

src/core/model/GFBuffer.cpp

@@ -31,10 +31,14 @@
 #include <openssl/crypto.h>
 #include <openssl/evp.h>
 
+#include <cstddef>
 #include <cstring>
 
 namespace GpgFrontend {
 
+// 16MB
+constexpr size_t kStrlenMaxLength = static_cast<const size_t>(16 * 1024 * 1024);
+
 struct GFBuffer::Impl {
   void* sec_ptr_ = nullptr;
   size_t sec_size_ = 0;
@@ -96,8 +100,8 @@ GFBuffer::GFBuffer(const QString& str) {
 }
 
 GFBuffer::GFBuffer(const char* str)
-    : impl_(SecureCreateSharedObject<Impl>((str != nullptr) ? std::strlen(str)
-                                                            : 0)) {
+    : impl_(SecureCreateSharedObject<Impl>(
+          (str != nullptr) ? strnlen(str, kStrlenMaxLength) : 0)) {
   if ((str != nullptr) && impl_->sec_size_ > 0) {
     std::memcpy(impl_->sec_ptr_, str, impl_->sec_size_);
   }
@@ -214,12 +218,12 @@ auto GFBuffer::ConvertToQString() const -> QString {
 }
 
 auto GFBuffer::operator==(const char* str) const -> bool {
-  return Size() == strlen(str) &&
+  return Size() == strnlen(str, kStrlenMaxLength) &&
          (Size() == 0 || std::memcmp(Data(), str, Size()) == 0);
 }
 
 auto GFBuffer::operator!=(const char* str) const -> bool {
-  return Size() == strlen(str) &&
+  return Size() == strnlen(str, kStrlenMaxLength) &&
          (Size() == 0 || std::memcmp(Data(), str, Size()) != 0);
 }
 

src/core/utils/IOUtils.cpp

@@ -48,9 +48,11 @@ auto GetFileHashOpenSSL(const QString& file_path, const EVP_MD* md_type)
   }
 
   GpgFrontend::GFBuffer buffer(GpgFrontend::kSecBufferSize);
+  const auto buffer_size = static_cast<qsizetype>(buffer.Size());
   while (!file.atEnd()) {
-    qint64 n = file.read(buffer.Data(), static_cast<qsizetype>(buffer.Size()));
-    if (n <= 0) break;
+    auto n = file.read(buffer.Data(), buffer_size);
+    if (n <= 0 || n > buffer_size) break;
+
     if (EVP_DigestUpdate(ctx, buffer.Data(), n) != 1) {
       EVP_MD_CTX_free(ctx);
       return {};
@@ -100,18 +102,11 @@ auto ReadFileGFBuffer(const QString& file_name) -> std::tuple<bool, GFBuffer> {
   }
 
   auto file_size = file.size();
-  if (file_size <= 0) {
-    file.close();
-    return {false, GFBuffer()};
-  }
+  if (file_size <= 0) return {false, GFBuffer()};
 
   GFBuffer buf(static_cast<size_t>(file_size));
   auto n = file.read(buf.Data(), file_size);
-  file.close();
-
-  if (n != file_size) {
-    return {false, GFBuffer()};
-  }
+  if (n <= 0 || n != file_size) return {false, GFBuffer()};
 
   return {true, std::move(buf)};
 }