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@xxxxxxxxxx>
Cc: Matt Fleming <matt.fleming@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Stephen Warren <swarren@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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..62e05cf 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),
+ (unsigned long)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
--
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