Returns an error immediately without sending IPC message when a font family n...

chrome/browser/renderer_host/render_sandbox_host_linux.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/renderer_host/render_sandbox_host_linux.h"
 
 #include <stdint.h>
 #include <unistd.h>
 #include <sys/uio.h>
 #include <sys/socket.h>
@@ skipping 82 matching lines @@
       }
     }
   }
 
  private:
   // ---------------------------------------------------------------------------
   // Requests from the renderer...
 
   void HandleRequestFromRenderer(int fd) {
     std::vector<int> fds;
-    static const unsigned kMaxMessageLength = 2048;
-    char buf[kMaxMessageLength];
+
+    // A FontConfigIPC::METHOD_MATCH message could be kMaxFontFamilyLength
+    // bytes long (this is the largest message type).
+    // 128 bytes padding are necessary so recvmsg() does not return MSG_TRUNC
+    // error for a maximum length message.
+    char buf[FontConfigInterface::kMaxFontFamilyLength + 128];
+
     const ssize_t len = base::RecvMsg(fd, buf, sizeof(buf), &fds);
-    if (len == -1)
+    if (len == -1) {
+      // TODO: should send an error reply, or the sender might block forever.
+      NOTREACHED()
+          << "Sandbox host message is larger than kMaxFontFamilyLength";
       return;
+    }
     if (fds.size() == 0)
       return;
 
     Pickle pickle(buf, len);
     void* iter = NULL;
 
     int kind;
     if (!pickle.ReadInt(&iter, &kind))
       goto error;
 
@@ skipping 245 matching lines @@
     _exit(0);
   }
 }
 
 RenderSandboxHostLinux::~RenderSandboxHostLinux() {
   if (init_) {
     HANDLE_EINTR(close(renderer_socket_));
     HANDLE_EINTR(close(childs_lifeline_fd_));
   }
 }