[openwrt/openwrt] firmware-utils/tplink-safeloader: soft-version magic is data length

[LEDE Commits]

stintel pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/6985a26e5999c2d090d0ab57e19fba490b888ced

commit 6985a26e5999c2d090d0ab57e19fba490b888ced
Author: Sander Vanheule <sander at svanheule.net>
AuthorDate: Sat Jul 11 22:58:07 2020 +0200

    firmware-utils/tplink-safeloader: soft-version magic is data length
    
    The soft-version partition actually contains a header and trailing data:
    * header: {data length, [zero]}
    * data: {version, bcd encoded date, revision}
    
    The data length is currently treated as a magic number, but should
    contain the length of the partition data.
    
    This header is also present the following partitions (non-exhaustive):
    * string-based soft-version
    * support-list
    
    Signed-off-by: Sander Vanheule <sander at svanheule.net>
---
 tools/firmware-utils/src/tplink-safeloader.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/firmware-utils/src/tplink-safeloader.c b/tools/firmware-utils/src/tplink-safeloader.c
index 501b396343..145e80855a 100644
--- a/tools/firmware-utils/src/tplink-safeloader.c
+++ b/tools/firmware-utils/src/tplink-safeloader.c
@@ -84,7 +84,7 @@ struct device_info {
 
 /** The content of the soft-version structure */
 struct __attribute__((__packed__)) soft_version {
-	uint32_t magic;
+	uint32_t data_len;
 	uint32_t zero;
 	uint8_t pad1;
 	uint8_t version_major;
@@ -2153,7 +2153,8 @@ static struct image_partition_entry make_soft_version(uint32_t rev) {
 
 	struct tm *tm = gmtime(&t);
 
-	s->magic = htonl(0x0000000c);
+	/* Partition contents size, minus 8 byte header and trailing byte */
+	s->data_len = htonl(entry.size-9);
 	s->zero = 0;
 	s->pad1 = 0xff;