From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Mukesh Kumar Chaurasiya <mchauras@linux.vnet.ibm.com>
Date: Thu, 9 Feb 2023 13:09:16 +0530
Subject: [PATCH] osdep/linux/hostdisk: Modify sector by sysfs as disk sector

The disk sector size provided by sysfs file system considers the sector
size of 512 irrespective of disk sector size, thus causing the read by
the GRUB to an incorrect offset from what was originally intended.

Considering the 512 sector size of sysfs data the actual sector needs to
be modified corresponding to disk sector size.

Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.vnet.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit f7564844f82b57078d601befadc438b5bc1fa01b)
---
 grub-core/osdep/linux/hostdisk.c | 7 ++++---
 include/grub/disk.h              | 7 +++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/grub-core/osdep/linux/hostdisk.c b/grub-core/osdep/linux/hostdisk.c
index 7bc99ac1c1..a9ea0bb465 100644
--- a/grub-core/osdep/linux/hostdisk.c
+++ b/grub-core/osdep/linux/hostdisk.c
@@ -240,7 +240,8 @@ have_devfs (void)
 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
 
 static int
-grub_hostdisk_linux_find_partition (char *dev, grub_disk_addr_t sector)
+grub_hostdisk_linux_find_partition (const grub_disk_t disk, char *dev,
+                                    grub_disk_addr_t sector)
 {
   size_t len = strlen (dev);
   const char *format;
@@ -305,7 +306,7 @@ grub_hostdisk_linux_find_partition (char *dev, grub_disk_addr_t sector)
       if (fstat (fd, &st) < 0
 	  || !grub_util_device_is_mapped_stat (&st)
 	  || !grub_util_get_dm_node_linear_info (st.st_rdev, 0, 0, &start))
-	start = grub_util_find_partition_start_os (real_dev);
+	start = grub_disk_to_native_sector (disk, grub_util_find_partition_start_os (real_dev));
       /* We don't care about errors here.  */
       grub_errno = GRUB_ERR_NONE;
 
@@ -386,7 +387,7 @@ grub_util_fd_open_device (const grub_disk_t disk, grub_disk_addr_t sector, int f
 	&& strncmp (dev, "/dev/", 5) == 0)
       {
 	if (sector >= part_start)
-	  is_partition = grub_hostdisk_linux_find_partition (dev, part_start);
+	  is_partition = grub_hostdisk_linux_find_partition (disk, dev, part_start);
 	else
 	  *max = part_start - sector;
       }
diff --git a/include/grub/disk.h b/include/grub/disk.h
index 06210a7049..881addcc77 100644
--- a/include/grub/disk.h
+++ b/include/grub/disk.h
@@ -208,6 +208,13 @@ grub_disk_from_native_sector (grub_disk_t disk, grub_disk_addr_t sector)
   return sector << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
 }
 
+/* Convert from GRUB native disk sized sector to disk sized sector. */
+static inline grub_disk_addr_t
+grub_disk_to_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);