Discussion:
[PATCH] msdos: Fix overflow in converting partition start and length into 512B blocks
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Michael Chang
2018-09-13 08:08:20 UTC
Permalink
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 <***@suse.com>
---
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
Daniel Kiper
2018-09-19 13:46:59 UTC
Permalink
Post by 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.
Reviewed-by: Daniel Kiper <***@oracle.com>

Daniel

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