Fix buffer allocation

b/15293123

Change-Id: Icb3ceabf02a55bc931baaf388ce125db6332de0e
diff --git a/media/mtp/MtpDataPacket.cpp b/media/mtp/MtpDataPacket.cpp
index c4f87a0..e6e19e3 100644
--- a/media/mtp/MtpDataPacket.cpp
+++ b/media/mtp/MtpDataPacket.cpp
@@ -363,7 +363,7 @@
 }
 
 int MtpDataPacket::writeData(int fd, void* data, uint32_t length) {
-    allocate(length);
+    allocate(length + MTP_CONTAINER_HEADER_SIZE);
     memcpy(mBuffer + MTP_CONTAINER_HEADER_SIZE, data, length);
     length += MTP_CONTAINER_HEADER_SIZE;
     MtpPacket::putUInt32(MTP_CONTAINER_LENGTH_OFFSET, length);