There is a hardcoded maximum disk size that can be read or written from,
currently set at 1EiB in grub_disk_adjust_range. Move the literal into a
macro in disk.h, so our assumptions are more visible. This hard coded limit
does not prevent using larger disks, just grub won't read/write past the
limit. The comment accompanying this restriction didn't quite make sense to
me, so its been modified.
Signed-off-by: Glenn Washburn <developm...@efficientek.com>
---
grub-core/kern/disk_common.c | 15 ++++++++-------
include/grub/disk.h | 6 ++++++
2 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/grub-core/kern/disk_common.c b/grub-core/kern/disk_common.c
index 2ca12b5f8..d43b927a4 100644
--- a/grub-core/kern/disk_common.c
+++ b/grub-core/kern/disk_common.c
@@ -32,13 +32,14 @@ grub_disk_adjust_range (grub_disk_t disk, grub_disk_addr_t
*sector,
/* Transform total_sectors to number of 512B blocks. */
total_sectors = disk->total_sectors << (disk->log_sector_size -
GRUB_DISK_SECTOR_BITS);
- /* Some drivers have problems with disks above reasonable.
- Treat unknown as 1EiB disk. While on it, clamp the size to 1EiB.
- Just one condition is enough since GRUB_DISK_UNKNOWN_SIZE << ls is always
- above 9EiB.
- */
- if (total_sectors > (1ULL << 51))
- total_sectors = (1ULL << 51);
+ /*
+ * Some drivers have problems with disks above reasonable sizes.
+ * Clamp the size to GRUB_DISK_MAX_SECTORS. Just one condition is enough
+ * since GRUB_DISK_UNKNOWN_SIZE is always above GRUB_DISK_MAX_SECTORS,
+ * assuming a maximum 4KiB sector size.
+ */
+ if (total_sectors > GRUB_DISK_MAX_SECTORS)
+ total_sectors = GRUB_DISK_MAX_SECTORS;
if ((total_sectors <= *sector
|| ((*offset + size + GRUB_DISK_SECTOR_SIZE - 1)
diff --git a/include/grub/disk.h b/include/grub/disk.h
index 132a1bb75..93f4ae226 100644
--- a/include/grub/disk.h
+++ b/include/grub/disk.h
@@ -161,6 +161,12 @@ typedef struct grub_disk_memberlist
*grub_disk_memberlist_t;
#define GRUB_DISK_SECTOR_SIZE 0x200
#define GRUB_DISK_SECTOR_BITS 9
+/*
+ * Some drivers have problems with disks above reasonable sizes.
+ * Set max disk size at 1EiB.
+ */
+#define GRUB_DISK_MAX_SECTORS (1ULL << (60 - GRUB_DISK_MAX_SECTORS))
+
/* The maximum number of disk caches. */
#define GRUB_DISK_CACHE_NUM 1021
--
2.27.0
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