[PATCH] partitions: efi: fix GPT header size exceeding allocation size

[PATCH] partitions: efi: fix GPT header size exceeding allocation size

[Abdelrahman Youssef]

The buffer gets allocated with the block device of size SECTOR_SIZE, but an
ill-formed GPT header_size may exceed it resulting in heap-overflow.

Signed-off-by: Abdelrahman Youssef <abdelrahmanyossef12@gmail.com>
---
 common/partitions/efi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/common/partitions/efi.c b/common/partitions/efi.c
index 829360da6e..9a04b7014d 100644
--- a/common/partitions/efi.c
+++ b/common/partitions/efi.c
@@ -173,6 +173,9 @@ static int is_gpt_valid(struct block_device *blk, u64 lba,
 		goto fail;
 	}
 
+	if (le32_to_cpu((*gpt)->header_size) > bdev_logical_block_size(blk))
+		goto fail;
+
 	/* Check the GUID Partition Table CRC */
 	origcrc = le32_to_cpu((*gpt)->header_crc32);
 	(*gpt)->header_crc32 = 0;
-- 
2.43.0

Re: [PATCH] partitions: efi: fix GPT header size exceeding allocation size

[Ahmad Fatoum]

Hello Abdelrahman,

Thanks for your patch.

On 22.10.24 18:27, Abdelrahman Youssef wrote:
> The buffer gets allocated with the block device of size SECTOR_SIZE, but an

I guess you meant to say here "with the length of the block device's sector size".

> ill-formed GPT header_size may exceed it resulting in heap-overflow.

Nice catch. Been there since nearly 10 years too:

Fixes: 760689e5ccf1 ("disk: partitions: add EFI GUID Partition Table")

> Signed-off-by: Abdelrahman Youssef <abdelrahmanyossef12@gmail.com>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

Cheers,
Ahmad

> ---
>  common/partitions/efi.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/common/partitions/efi.c b/common/partitions/efi.c
> index 829360da6e..9a04b7014d 100644
> --- a/common/partitions/efi.c
> +++ b/common/partitions/efi.c
> @@ -173,6 +173,9 @@ static int is_gpt_valid(struct block_device *blk, u64 lba,
>  		goto fail;
>  	}
>  
> +	if (le32_to_cpu((*gpt)->header_size) > bdev_logical_block_size(blk))
> +		goto fail;
> +
>  	/* Check the GUID Partition Table CRC */
>  	origcrc = le32_to_cpu((*gpt)->header_crc32);
>  	(*gpt)->header_crc32 = 0;


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |