[PATCH v2 1/2] cmd: mvebu/bubt: Check for A38x image data checksum

Pali Rohár
2022-08-09T19:42:26Z

Currently for A38x image is checked only header checksum.
So check also for image data checksum to prevent flashing broken image.

Signed-off-by: Pali Rohár <pali@kernel.org>

---
Changes in v2:
* Compile fix (move code chunk from patch 2/2 to 1/2)
---
cmd/mvebu/bubt.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/cmd/mvebu/bubt.c b/cmd/mvebu/bubt.c
index 2136af64163c..3b6ffb7ffd1f 100644
--- a/cmd/mvebu/bubt.c
+++ b/cmd/mvebu/bubt.c
@@ -688,9 +688,24 @@ static uint8_t image_checksum8(const void *start, size_t len)
return csum;
}

+static uint32_t image_checksum32(const void *start, size_t len)
+{
+ u32 csum = 0;
+ const u32 *p = start;
+
+ while (len) {
+ csum += *p;
+ ++p;
+ len -= sizeof(u32);
+ }
+
+ return csum;
+}
+
static int check_image_header(void)
{
u8 checksum;
+ u32 checksum32, exp_checksum32;
const struct a38x_main_hdr_v1 *hdr =
(struct a38x_main_hdr_v1 *)get_load_addr();
const size_t image_size = a38x_header_size(hdr);
@@ -701,11 +716,39 @@ static int check_image_header(void)
checksum = image_checksum8(hdr, image_size);
checksum -= hdr->checksum;
if (checksum != hdr->checksum) {
- printf("Error: Bad A38x image checksum. 0x%x != 0x%x\n",
+ printf("Error: Bad A38x image header checksum. 0x%x != 0x%x\n",
checksum, hdr->checksum);
return -ENOEXEC;
}

+ offset = le32_to_cpu(hdr->srcaddr);
+ size = le32_to_cpu(hdr->blocksize);
+
+ if (hdr->blockid == 0x78) { /* SATA id */
+ if (offset < 1) {
+ printf("Error: Bad A38x image srcaddr.\n");
+ return -ENOEXEC;
+ }
+ offset -= 1;
+ offset *= 512;
+ }
+
+ if (hdr->blockid == 0xAE) /* SDIO id */
+ offset *= 512;
+
+ if (offset % 4 != 0 || size < 4 || size % 4 != 0) {
+ printf("Error: Bad A38x image blocksize.\n");
+ return -ENOEXEC;
+ }
+
+ checksum32 = image_checksum32((u8 *)hdr + offset, size - 4);
+ exp_checksum32 = *(u32 *)((u8 *)hdr + offset + size - 4);
+ if (checksum32 != exp_checksum32) {
+ printf("Error: Bad A38x image data checksum. 0x%08x != 0x%08x\n",
+ checksum32, exp_checksum32);
+ return -ENOEXEC;
+ }
+
printf("Image checksum...OK!\n");
return 0;
}
--
2.20.1