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

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Message-ID: <1346836723.2559.6.camel@offbook>
Date:	Wed, 05 Sep 2012 11:18:43 +0200
From:	Davidlohr Bueso <dave@....org>
To:	Jens Axboe <axboe@...nel.dk>, Matt Domsch <Matt_Domsch@...l.com>
Cc:	lkml <linux-kernel@...r.kernel.org>
Subject: [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 <dave@....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@....org>
+ * - tighten GPT header integrity verification.
+ *
  * Mon Nov 09 2004 Matt Domsch <Matt_Domsch@...l.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




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