[PATCH] msdos: Fix overflow in converting partition start and length into 512B blocks

[Michael Chang]

When booting from NVME SSD with 4k sector size, it fails with the message.

error: attempt to read or write outside of partition.

This patch fixes the problem by fixing overflow in converting partition start
and length into 512B blocks.

Signed-off-by: Michael Chang <address@hidden>
---
 grub-core/partmap/msdos.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/grub-core/partmap/msdos.c b/grub-core/partmap/msdos.c
index 6d4b455a1..7b8e45076 100644
--- a/grub-core/partmap/msdos.c
+++ b/grub-core/partmap/msdos.c
@@ -175,9 +175,9 @@ grub_partition_msdos_iterate (grub_disk_t disk,
          e = mbr.entries + p.index;
 
          p.start = p.offset
-           + (grub_le_to_cpu32 (e->start)
+           + ((grub_disk_addr_t)grub_le_to_cpu32 (e->start)
               << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS)) - delta;
-         p.len = grub_le_to_cpu32 (e->length)
+         p.len = (grub_uint64_t)grub_le_to_cpu32 (e->length)
            << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
          p.msdostype = e->type;
 
@@ -210,7 +210,7 @@ grub_partition_msdos_iterate (grub_disk_t disk,
          if (grub_msdos_partition_is_extended (e->type))
            {
              p.offset = ext_offset
-               + (grub_le_to_cpu32 (e->start)
+               + ((grub_disk_addr_t)grub_le_to_cpu32 (e->start)
                   << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS));
              if (! ext_offset)
                ext_offset = p.offset;
@@ -294,9 +294,9 @@ pc_partition_map_embed (struct grub_disk *disk, unsigned 
int *nsectors,
 
          if (!grub_msdos_partition_is_empty (e->type)
              && end > offset
-             + (grub_le_to_cpu32 (e->start)
+             + ((grub_disk_addr_t)grub_le_to_cpu32 (e->start)
                 << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS)))
-           end = offset + (grub_le_to_cpu32 (e->start)
+           end = offset + ((grub_disk_addr_t)grub_le_to_cpu32 (e->start)
                            << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS));
 
          /* If this is a GPT partition, this MBR is just a dummy.  */
@@ -312,7 +312,7 @@ pc_partition_map_embed (struct grub_disk *disk, unsigned 
int *nsectors,
          if (grub_msdos_partition_is_extended (e->type))
            {
              offset = ext_offset 
-               + (grub_le_to_cpu32 (e->start) 
+               + ((grub_disk_addr_t)grub_le_to_cpu32 (e->start)
                   << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS));
              if (! ext_offset)
                ext_offset = offset;
-- 
2.13.6