altos/flash-loader: Check memory addresses against flash space

This validates memory read/write requests to make sure they are within
the available flash memory space.

This also reports the flash base and bounds addresses in the 'version'
command so that the loader can validate the image before attempting to
write it.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 35 insertions, 4 deletions

diff --git a/src/product/ao_flash_task.c b/src/product/ao_flash_task.c
index 6cb308e1..9a12add6 100644
--- a/src/product/ao_flash_task.c
+++ b/src/product/ao_flash_task.c
@@ -79,6 +79,14 @@ ao_block_erase(void)
 	ao_flash_erase_page(p);
 }
 
+static int
+ao_block_valid_address(uint32_t addr)
+{
+	if ((uint32_t) AO_BOOT_APPLICATION_BASE <= addr && addr <= (uint32_t) AO_BOOT_APPLICATION_BOUND - 256)
+		return 1;
+	return 0;
+}
+
 static void
 ao_block_write(void)
 {
@@ -87,12 +95,10 @@ ao_block_write(void)
 	uint8_t		data[256];
 	uint16_t	i;
 
-	if (addr < (uint32_t) AO_BOOT_APPLICATION_BASE) {
-		ao_put_string("Invalid address\n");
-		return;
-	}
 	for (i = 0; i < 256; i++)
 		data[i] = ao_usb_getchar();
+	if (!ao_block_valid_address(addr))
+		return;
 	ao_flash_page(p, (void *) data);
 }
 
@@ -104,18 +110,43 @@ ao_block_read(void)
 	uint16_t	i;
 	uint8_t		c;
 
+	if (!ao_block_valid_address(addr)) {
+		for (i = 0; i < 256; i++)
+			ao_usb_putchar(0xff);
+		return;
+	}
 	for (i = 0; i < 256; i++) {
 		c = *p++;
 		ao_usb_putchar(c);
 	}
 }
 
+static inline void
+hexchar(uint8_t c)
+{
+	if (c > 10)
+		c += 'a' - ('9' + 1);
+	ao_usb_putchar(c + '0');
+}
+
+static void
+ao_put_hex(uint32_t u)
+{
+	int8_t i;
+	for (i = 28; i >= 0; i -= 4)
+		hexchar((u >> i) & 0xf);
+}
+
 static void
 ao_show_version(void)
 {
 	ao_put_string("altos-loader");
 	ao_put_string("\nmanufacturer     "); ao_put_string(ao_manufacturer);
 	ao_put_string("\nproduct          "); ao_put_string(ao_product);
+	ao_put_string("\nflash-range      ");
+	ao_put_hex((uint32_t) AO_BOOT_APPLICATION_BASE);
+	ao_usb_putchar(' ');
+	ao_put_hex((uint32_t) AO_BOOT_APPLICATION_BOUND);
 	ao_put_string("\nsoftware-version "); ao_put_string(ao_version);
 	ao_put_string("\n");
 }