[PATCH v2 1/1] Fix integer overflow at left shift expression on i386-pc platform

[Maxim Fomin]

>From 5db28aa0cb98e906adc7cb735bfa1979ce32c228 Mon Sep 17 00:00:00 2001
From: Maxim Fomin <maxim@fomin.one>
Date: Sat, 17 Dec 2022 18:11:34 +0000
Subject: [PATCH v2 1/1] Fix integer overflow at left shift expression on
 i386-pc platform.

In case of large partitions (>1TiB) left shift
expression with unsigned 'length' object and
signed GRUB_DISK_SECTOR_BITS macro may cause
integer overflow making calculated partition
size less than true value. This issue is fixed
by increasing the size of 'length' integer type
and casting GRUB_DISK_SECTOR_BITS to unsigned
type prior to shift expression.

Signed-off-by: Maxim Fomin <maxim@fomin.one>
---
 grub-core/kern/fs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/grub-core/kern/fs.c b/grub-core/kern/fs.c
index b9508296d..c196f2bf1 100644
--- a/grub-core/kern/fs.c
+++ b/grub-core/kern/fs.c
@@ -130,7 +130,7 @@ grub_fs_probe (grub_device_t device)
 struct grub_fs_block
 {
   grub_disk_addr_t offset;
-  unsigned long length;
+  grub_disk_addr_t length;
 };
 
 static grub_err_t
@@ -195,7 +195,7 @@ grub_fs_blocklist_open (grub_file_t file, const char *name)
          goto fail;
        }
 
-      file->size += (blocks[i].length << GRUB_DISK_SECTOR_BITS);
+      file->size += (blocks[i].length << (grub_disk_addr_t) 
GRUB_DISK_SECTOR_BITS);
       p++;
     }
 
-- 
2.39.0