[CRYPTO-LUKS v2 03/19] cryptodisk: Incorrect calculation of sector in grub_cryptodisk_read/write.

[Glenn Washburn]

Here dev is a grub_cryptodisk_t and dev->offset is offset in sectors of size
native to the cryptodisk device. The sector is correctly transformed into
native grub sector size, but then added to dev->offset which is not
transformed. Create function grub_disk_from_native_sector to do the native
disk sector to grub sector size conversion.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/cryptodisk.c | 12 +++++-------
 include/grub/disk.h         |  7 +++++++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index b87925ad3..b3610a1b6 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -761,10 +761,10 @@ grub_cryptodisk_read (grub_disk_t disk, grub_disk_addr_t 
sector,
                PRIxGRUB_UINT64_T " with offset of %" PRIuGRUB_UINT64_T "\n",
                size, sector, dev->offset);
 
+  sector = sector + dev->offset;
   err = grub_disk_read (dev->source_disk,
-                       (sector << (disk->log_sector_size
-                                  - GRUB_DISK_SECTOR_BITS)) + dev->offset, 0,
-                       size << disk->log_sector_size, buf);
+                       grub_disk_from_native_sector (disk, sector),
+                       0, size << disk->log_sector_size, buf);
   if (err)
     {
       grub_dprintf ("cryptodisk", "grub_disk_read failed with error %d\n", 
err);
@@ -821,12 +821,10 @@ grub_cryptodisk_write (grub_disk_t disk, grub_disk_addr_t 
sector,
     }
 
   /* Since ->write was called so disk.mod is loaded but be paranoid  */
-  
+  sector = sector + dev->offset;
   if (grub_disk_write_weak)
     err = grub_disk_write_weak (dev->source_disk,
-                               (sector << (disk->log_sector_size
-                                           - GRUB_DISK_SECTOR_BITS))
-                               + dev->offset,
+                               grub_disk_from_native_sector (disk, sector),
                                0, size << disk->log_sector_size, tmp);
   else
     err = grub_error (GRUB_ERR_BUG, "disk.mod not loaded");
diff --git a/include/grub/disk.h b/include/grub/disk.h
index 316659fee..af9f886d3 100644
--- a/include/grub/disk.h
+++ b/include/grub/disk.h
@@ -174,6 +174,13 @@ typedef struct grub_disk_memberlist 
*grub_disk_memberlist_t;
 /* Return value of grub_disk_get_size() in case disk size is unknown. */
 #define GRUB_DISK_SIZE_UNKNOWN  0xffffffffffffffffULL
 
+/* Convert to grub native disk sized sector from disk sized sector */
+static inline grub_disk_addr_t
+grub_disk_from_native_sector (grub_disk_t disk, grub_disk_addr_t sector)
+{
+  return sector << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
+}
+
 /* This is called from the memory manager.  */
 void grub_disk_cache_invalidate_all (void);
 
-- 
2.27.0