From ec20b7ed9d7886b26ea0431a40eee6b06d384f53 Mon Sep 17 00:00:00 2001
From: Matthew Kennedy <makenne@microsoft.com>
Date: Thu, 10 Dec 2020 17:58:02 -0800
Subject: [PATCH] validate flash request

---
 firmware/bootloader/bootloader.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/firmware/bootloader/bootloader.cpp b/firmware/bootloader/bootloader.cpp
index d018331..2abdecf 100644
--- a/firmware/bootloader/bootloader.cpp
+++ b/firmware/bootloader/bootloader.cpp
@@ -151,7 +151,16 @@ void RunBootloaderLoop()
             case 0x02: // opcode 2 is "write flash data"
                 // Embedded data is the flash address
 
-                Flash::Write(appFlashAddr + embeddedData, &frame.data8[0], frame.DLC);
+                // Don't allow misaligned writes
+                if (embeddedData % sizeof(flashdata_t) != 0 || frame.DLC % sizeof(flashdata_t) != 0)
+                {
+                    sendNak();
+                }
+                else
+                {
+                    Flash::Write(appFlashAddr + embeddedData, &frame.data8[0], frame.DLC);
+                    sendAck();
+                }
 
                 break;
             case 0x03: // opcode 3 is "boot app"