* [PATCH] Ensure that the GPT header is at least the size of the structure.
@ 2013-02-13 23:09 Peter Jones
2013-02-13 23:15 ` Peter Jones
0 siblings, 1 reply; 3+ messages in thread
From: Peter Jones @ 2013-02-13 23:09 UTC (permalink / raw)
To: Matt Fleming
Cc: Jens Axboe, linux-kernel, Andrew Morton, Stephen Warren,
Peter Jones
UEFI 2.3.1D will include a change to the spec language mandating that a
GPT header must be greater than *or equal to* the size of the defined
structure. While verifying that this would work on Linux, I discovered
that we're not actually checking the minimum bound at all.
The result of this is that when we verify the checksum, it's possible
that on a malformed header (with header_size of 0), we won't actually
verify any data.
Signed-off-by: Peter Jones <pjones@redhat.com>
---
block/partitions/efi.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index b62fb88..5ad168c 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -310,15 +310,23 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
goto fail;
}
- /* Check the GUID Partition Table header size */
+ /* Check the GUID Partition Table header size is too big */
if (le32_to_cpu((*gpt)->header_size) >
bdev_logical_block_size(state->bdev)) {
- pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
+ pr_debug("GUID Partition Table Header size is too large: %u > %u\n",
le32_to_cpu((*gpt)->header_size),
bdev_logical_block_size(state->bdev));
goto fail;
}
+ /* Check the GUID Partition Table header size is too small */
+ if (le32_to_cpu((*gpt)->header_size) < sizeof(gpt_header)) {
+ pr_debug("GUID Partition Table Header size is too small: %u < %u\n",
+ le32_to_cpu((*gpt)->header_size),
+ sizeof(gpt_header));
+ goto fail;
+ }
+
/* Check the GUID Partition Table CRC */
origcrc = le32_to_cpu((*gpt)->header_crc32);
(*gpt)->header_crc32 = 0;
--
1.8.1.2
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH] Ensure that the GPT header is at least the size of the structure.
2013-02-13 23:09 [PATCH] Ensure that the GPT header is at least the size of the structure Peter Jones
@ 2013-02-13 23:15 ` Peter Jones
2013-02-14 9:13 ` Matt Fleming
0 siblings, 1 reply; 3+ messages in thread
From: Peter Jones @ 2013-02-13 23:15 UTC (permalink / raw)
To: Matt Fleming
Cc: Jens Axboe, linux-kernel, Andrew Morton, Stephen Warren,
Peter Jones
UEFI 2.3.1D will include a change to the spec language mandating that a
GPT header must be greater than *or equal to* the size of the defined
structure. While verifying that this would work on Linux, I discovered
that we're not actually checking the minimum bound at all.
The result of this is that when we verify the checksum, it's possible
that on a malformed header (with header_size of 0), we won't actually
verify any data.
(ammended to fix type error in pr_debug())
Signed-off-by: Peter Jones <pjones@redhat.com>
---
block/partitions/efi.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index b62fb88..a7475e7 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -310,15 +310,23 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
goto fail;
}
- /* Check the GUID Partition Table header size */
+ /* Check the GUID Partition Table header size is too big */
if (le32_to_cpu((*gpt)->header_size) >
bdev_logical_block_size(state->bdev)) {
- pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
+ pr_debug("GUID Partition Table Header size is too large: %u > %u\n",
le32_to_cpu((*gpt)->header_size),
bdev_logical_block_size(state->bdev));
goto fail;
}
+ /* Check the GUID Partition Table header size is too small */
+ if (le32_to_cpu((*gpt)->header_size) < sizeof(gpt_header)) {
+ pr_debug("GUID Partition Table Header size is too small: %u < %lu\n",
+ le32_to_cpu((*gpt)->header_size),
+ sizeof(gpt_header));
+ goto fail;
+ }
+
/* Check the GUID Partition Table CRC */
origcrc = le32_to_cpu((*gpt)->header_crc32);
(*gpt)->header_crc32 = 0;
--
1.8.1.2
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] Ensure that the GPT header is at least the size of the structure.
2013-02-13 23:15 ` Peter Jones
@ 2013-02-14 9:13 ` Matt Fleming
0 siblings, 0 replies; 3+ messages in thread
From: Matt Fleming @ 2013-02-14 9:13 UTC (permalink / raw)
To: Peter Jones; +Cc: Jens Axboe, linux-kernel, Andrew Morton, Stephen Warren
On Wed, 2013-02-13 at 18:15 -0500, Peter Jones wrote:
> UEFI 2.3.1D will include a change to the spec language mandating that a
> GPT header must be greater than *or equal to* the size of the defined
> structure. While verifying that this would work on Linux, I discovered
> that we're not actually checking the minimum bound at all.
>
> The result of this is that when we verify the checksum, it's possible
> that on a malformed header (with header_size of 0), we won't actually
> verify any data.
>
> (ammended to fix type error in pr_debug())
>
> Signed-off-by: Peter Jones <pjones@redhat.com>
> ---
> block/partitions/efi.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/block/partitions/efi.c b/block/partitions/efi.c
> index b62fb88..a7475e7 100644
> --- a/block/partitions/efi.c
> +++ b/block/partitions/efi.c
> @@ -310,15 +310,23 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
> goto fail;
> }
>
> - /* Check the GUID Partition Table header size */
> + /* Check the GUID Partition Table header size is too big */
> if (le32_to_cpu((*gpt)->header_size) >
> bdev_logical_block_size(state->bdev)) {
> - pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
> + pr_debug("GUID Partition Table Header size is too large: %u > %u\n",
> le32_to_cpu((*gpt)->header_size),
> bdev_logical_block_size(state->bdev));
> goto fail;
> }
>
> + /* Check the GUID Partition Table header size is too small */
> + if (le32_to_cpu((*gpt)->header_size) < sizeof(gpt_header)) {
> + pr_debug("GUID Partition Table Header size is too small: %u < %lu\n",
> + le32_to_cpu((*gpt)->header_size),
> + sizeof(gpt_header));
> + goto fail;
> + }
> +
> /* Check the GUID Partition Table CRC */
> origcrc = le32_to_cpu((*gpt)->header_crc32);
> (*gpt)->header_crc32 = 0;
Seems straight forward.
Acked-by: Matt Fleming <matt.fleming@intel.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-02-14 9:13 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-02-13 23:09 [PATCH] Ensure that the GPT header is at least the size of the structure Peter Jones
2013-02-13 23:15 ` Peter Jones
2013-02-14 9:13 ` Matt Fleming
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox