[PATCH 1/3] partitions: efi: compare first and last usable LBAs

[Davidlohr Bueso]

When verifying GPT header integrity, make sure that
first usable LBA is smaller than last usable LBA.

Signed-off-by: Davidlohr Bueso <dave@xxxxxxx>
---
 block/partitions/efi.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 6296b40..7795bb4 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -344,6 +344,12 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
 	 * within the disk.
 	 */
 	lastlba = last_lba(state->bdev);
+	if (le64_to_cpu((*gpt)->last_usable_lba) < le64_to_cpu((*gpt)->first_usable_lba)) {
+		pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
+			 (unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
+			 (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba));
+		goto fail;
+	}
 	if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
 		pr_debug("GPT: first_usable_lba incorrect: %lld > %lld\n",
 			 (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba),
-- 
1.7.4.1




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