[PATCH v4 12/15] luks2: grub_cryptodisk_t->total_length is the max number of device native sectors

[Glenn Washburn]

The total_length field is named confusingly because length usually refers to
bytes, whereas in this case its really the total number of sectors on the
device. Also counter-intuitively, grub_disk_get_size returns the total
number of device native sectors. We need to convert the sectors from the
size of the underlying device to the cryptodisk sector size. And
segment.size is in bytes which need to be converted to cryptodisk sectors.

Also, removed an empty statement.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/luks2.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index ca830d73b..355bb4aec 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -429,7 +429,7 @@ luks2_decrypt_key (grub_uint8_t *out_key,
   grub_uint8_t salt[GRUB_CRYPTODISK_MAX_KEYLEN];
   grub_uint8_t *split_key = NULL;
   grub_size_t saltlen = sizeof (salt);
-  char cipher[32], *p;;
+  char cipher[32], *p;
   const gcry_md_spec_t *hash;
   gcry_err_code_t gcry_ret;
   grub_err_t ret;
@@ -615,9 +615,10 @@ luks2_recover_key (grub_disk_t source,
       crypt->log_sector_size = sizeof (unsigned int) * 8
                - __builtin_clz ((unsigned int) segment.sector_size) - 1;
       if (grub_strcmp (segment.size, "dynamic") == 0)
-       crypt->total_sectors = grub_disk_get_size (source) - 
crypt->offset_sectors;
+       crypt->total_sectors = (grub_disk_get_size (source) >> 
(crypt->log_sector_size - source->log_sector_size))
+                              - crypt->offset_sectors;
       else
-       crypt->total_sectors = grub_strtoull (segment.size, NULL, 10);
+       crypt->total_sectors = grub_strtoull (segment.size, NULL, 10) >> 
crypt->log_sector_size;
 
       ret = luks2_decrypt_key (candidate_key, source, crypt, &keyslot,
                               (const grub_uint8_t *) passphrase, grub_strlen 
(passphrase));
-- 
2.27.0