[RFC PATCH 1/3] bootconfig: Use hexadecimal ASCII string for size and checksum

[Masami Hiramatsu]

To make the bootconfig format more platform independent, use
8-bytes hexadecimal ASCII string for size and checksum field
in the footer. This will allow us to apply bootconfig to the
cross build initrd without caring the endianness.

Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
 init/main.c |   20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/init/main.c b/init/main.c
index 20baced721ad..b82f23cff709 100644
--- a/init/main.c
+++ b/init/main.c
@@ -267,8 +267,8 @@ early_param("loglevel", loglevel);
 static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
 {
        u32 size, csum;
+       char buf[9];
        char *data;
-       u32 *hdr;
        int i;
 
        if (!initrd_end)
@@ -287,11 +287,21 @@ static void * __init get_boot_config_from_initrd(u32 
*_size, u32 *_csum)
        return NULL;
 
 found:
-       hdr = (u32 *)(data - 8);
-       size = hdr[0];
-       csum = hdr[1];
+       buf[8] = '\0';
+       data -= 8;
+       memcpy(buf, data, 8);
+       if (kstrtou32(buf, 16, &csum) != 0) {
+               pr_err("bootconfig checksum field is invalid\n");
+               return NULL;
+       }
+       data -= 8;
+       memcpy(buf, data, 8);
+       if (kstrtou32(buf, 16, &size) != 0) {
+               pr_err("bootconfig size field is invalid\n");
+               return NULL;
+       }
+       data -= size;
 
-       data = ((void *)hdr) - size;
        if ((unsigned long)data < initrd_start) {
                pr_err("bootconfig size %d is greater than initrd size %ld\n",
                        size, initrd_end - initrd_start);