ensure that UnixDomainSocket::RecvMsgWithFlags doesn't memcpy from 0

base/posix/unix_domain_socket_linux.cc

 // Copyright (c) 2011 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 "base/posix/unix_domain_socket_linux.h"
 
 #include <errno.h>
 #include <sys/socket.h>
 #include <sys/uio.h>
 #include <unistd.h>
@@ skipping 88 matching lines @@
     }
   }
 
   if (msg.msg_flags & MSG_TRUNC || msg.msg_flags & MSG_CTRUNC) {
     for (unsigned i = 0; i < wire_fds_len; ++i)
       close(wire_fds[i]);
     errno = EMSGSIZE;
     return -1;
   }
 
-  fds->resize(wire_fds_len);
-  memcpy(vector_as_array(fds), wire_fds, sizeof(int) * wire_fds_len);
+  if (wire_fds) {
+    fds->resize(wire_fds_len);
+    memcpy(vector_as_array(fds), wire_fds, sizeof(int) * wire_fds_len);
+  }
 
   return r;
 }
 
 // static
 ssize_t UnixDomainSocket::SendRecvMsg(int fd,
                                       uint8_t* reply,
                                       unsigned max_reply_len,
                                       int* result_fd,
                                       const Pickle& request) {
@@ skipping 43 matching lines @@
     NOTREACHED();
 
     return -1;
   }
 
   if (result_fd)
     *result_fd = fd_vector.empty() ? -1 : fd_vector[0];
 
   return reply_len;
 }