On Sun, 04 Dec 2022 13:06:37 +0000
Maxim Fomin <ma...@fomin.one> wrote:
> From db82faafba5e7eccd9fd6c0b7314f7322c1aecbd Mon Sep 17 00:00:00 2001
> From: Maxim Fomin <ma...@fomin.one>
> Date: Sun, 4 Dec 2022 12:05:34 +0000
> Subject: [PATCH] Fix integer overflow at left shift expression.
>
> In case of large partitions (>1TiB) left shift
> with signed int GRUB_DISK_SECTOR_BITS macro may
> cause integer overflow which results in wrong
> partition size.
> ---
> 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++;
Is this change actually necessary? You're making sure that
GRUB_DISK_SECTOR_BITS is treated as a 64-bit integer, but it would be
crazy for it to even be more than an 8 bit integer. Is there some other
desirable effect of this?
> }
>
Glenn
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