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partitions: efi: check minimum header size

PATCH New Davidlohr Bueso 1 participant 1 message Sep 5, 2012

Subsystems (2)
Block layer GUID partition table (GPT)
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Davidlohr Bueso

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

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 <[email protected]>
---
 block/partitions/efi.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
block/partitions/efi.c +5 -2
index abf33a2..3a5114e 100644
@@ -25,6 +25,9 @@
  * TODO:
  *
  * Changelog:
+ * Sept. 2012 Davidlohr Bueso <[email protected]>
+ * - tighten GPT header integrity verification.
+ *
  * Mon Nov 09 2004 Matt Domsch <[email protected]>
  * - 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));
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