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gpt: do not use disk sizes GRUB will reject as invalid later on

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GRUB assumes that no disk is ever larger than 1EiB and rejects
reads/writes to such locations. Unfortunately this is not conveyed in
the usual way with the special GRUB_DISK_SIZE_UNKNOWN value.
This commit is contained in:
Michael Marineau 2016-07-25 14:59:29 -07:00
parent a1724dace5
commit a8ad608425
1 changed files with 24 additions and 2 deletions
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26
grub-core/lib/gpt.c
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@ -143,6 +143,28 @@ grub_gpt_size_to_sectors (grub_gpt_t gpt, grub_size_t size)
return sectors; return sectors;
} }
/* Copied from grub-core/kern/disk_common.c grub_disk_adjust_range so we can
* avoid attempting to use disk->total_sectors when GRUB won't let us.
* TODO: Why is disk->total_sectors not set to GRUB_DISK_SIZE_UNKNOWN? */
static int
grub_gpt_disk_size_valid (grub_disk_t disk)
{
grub_disk_addr_t total_sectors;
/* 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))
return 0;
return 1;
}
static void static void
grub_gpt_lecrc32 (grub_uint32_t *crc, const void *data, grub_size_t len) grub_gpt_lecrc32 (grub_uint32_t *crc, const void *data, grub_size_t len)
{ {
@ -242,7 +264,7 @@ grub_gpt_read_backup (grub_disk_t disk, grub_gpt_t gpt)
grub_disk_addr_t addr; grub_disk_addr_t addr;
/* Assumes gpt->log_sector_size == disk->log_sector_size */ /* Assumes gpt->log_sector_size == disk->log_sector_size */
if (disk->total_sectors != GRUB_DISK_SIZE_UNKNOWN) if (grub_gpt_disk_size_valid(disk))
sector = disk->total_sectors - 1; sector = disk->total_sectors - 1;
else if (gpt->status & GRUB_GPT_PRIMARY_HEADER_VALID) else if (gpt->status & GRUB_GPT_PRIMARY_HEADER_VALID)
sector = grub_le_to_cpu64 (gpt->primary.alternate_lba); sector = grub_le_to_cpu64 (gpt->primary.alternate_lba);
@ -394,7 +416,7 @@ grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt)
return grub_error (GRUB_ERR_BUG, "No valid GPT header"); return grub_error (GRUB_ERR_BUG, "No valid GPT header");
/* Relocate backup to end if disk whenever possible. */ /* Relocate backup to end if disk whenever possible. */
if (disk->total_sectors != GRUB_DISK_SIZE_UNKNOWN) if (grub_gpt_disk_size_valid(disk))
backup_header = disk->total_sectors - 1; backup_header = disk->total_sectors - 1;
backup_entries = backup_header - backup_entries = backup_header -