[PATCH 3/3] partitions: efi: check minimum header size

[PATCH 3/3] partitions: efi: check minimum header size

[Davidlohr Bueso]

As per UEFI specs 2.3.1 (June 2012),
"The Header Size must be greater than 92 and must be less than
or equal to the logical block size"

Signed-off-by: Davidlohr Bueso <dave@gnu.org>
---
 block/partitions/efi.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index abf33a2..3a5114e 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -25,6 +25,9 @@
  * TODO:
  *
  * Changelog:
+ * Sept. 2012 Davidlohr Bueso <dave@gnu.org>
+ * - tighten GPT header integrity verification.
+ *
  * Mon Nov 09 2004 Matt Domsch <Matt_Domsch@dell.com>
  * - test for valid PMBR and valid PGPT before ever reading
  *   AGPT, allow override with 'gpt' kernel command line option.
@@ -311,8 +314,8 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
 	}
 
 	/* Check the GUID Partition Table header size */
-	if (le32_to_cpu((*gpt)->header_size) >
-			bdev_logical_block_size(state->bdev)) {
+	if (le32_to_cpu((*gpt)->header_size) <= 92 ||
+	    le32_to_cpu((*gpt)->header_size) > bdev_logical_block_size(state->bdev)) {
 		pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
 			le32_to_cpu((*gpt)->header_size),
 			bdev_logical_block_size(state->bdev));
-- 
1.7.4.1