Fixed bootloaders accepting flash writes to the bootloader region (thanks to NicoHood).

[pub/USBasp.git] / Bootloaders / HID / BootloaderHID.c

diff --git a/Bootloaders/HID/BootloaderHID.c b/Bootloaders/HID/BootloaderHID.c
index c21bf56..e5b7d32 100644 (file)
--- a/Bootloaders/HID/BootloaderHID.c
+++ b/Bootloaders/HID/BootloaderHID.c
@@ -152,6 +152,10 @@ void EVENT_USB_Device_ControlRequest(void)
                        uint16_t PageAddress = Endpoint_Read_16_LE();
                        #endif
 
+                       /* Determine if the given page address is correctly aligned to the
+                          start of a flash page. */
+                       bool PageAddressIsAligned = !(PageAddress & (SPM_PAGESIZE - 1));
+
                        /* Check if the command is a program page command, or a start application command */
                        #if (FLASHEND > 0xFFFF)
                        if ((uint16_t)(PageAddress >> 8) == COMMAND_STARTAPPLICATION)
@@ -161,7 +165,7 @@ void EVENT_USB_Device_ControlRequest(void)
                        {
                                RunBootloader = false;
                        }
-                       else if (PageAddress < BOOT_START_ADDR)
+                       else if ((PageAddress < BOOT_START_ADDR) && PageAddressIsAligned)
                        {
                                /* Erase the given FLASH page, ready to be programmed */
                                ATOMIC_BLOCK(ATOMIC_RESTORESTATE)