From d2f9096444d50dba8059d58fb6fe29be99256899 Mon Sep 17 00:00:00 2001
From: Michael Marineau <michael.marineau@coreos.com>
Date: Wed, 21 Sep 2016 14:55:19 -0700
Subject: [PATCH] gpt: always revalidate when recomputing checksums

This ensures all code modifying GPT data include the same sanity check
that repair does. If revalidation fails the status flags are left in the
appropriate state.
---
 grub-core/lib/gpt.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/grub-core/lib/gpt.c b/grub-core/lib/gpt.c
index 1b7e219f6..204e53b04 100644
--- a/grub-core/lib/gpt.c
+++ b/grub-core/lib/gpt.c
@@ -623,23 +623,9 @@ grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt)
   else
     return grub_error (GRUB_ERR_BUG, "No valid GPT");
 
-  /* Recompute checksums.  */
   if (grub_gpt_update_checksums (gpt))
     return grub_errno;
 
-  /* Sanity check.  */
-  if (grub_gpt_check_primary (gpt))
-    return grub_error (GRUB_ERR_BUG, "Generated invalid GPT primary header");
-
-  gpt->status |= (GRUB_GPT_PRIMARY_HEADER_VALID |
-		  GRUB_GPT_PRIMARY_ENTRIES_VALID);
-
-  if (grub_gpt_check_backup (gpt))
-    return grub_error (GRUB_ERR_BUG, "Generated invalid GPT backup header");
-
-  gpt->status |= (GRUB_GPT_BACKUP_HEADER_VALID |
-		  GRUB_GPT_BACKUP_ENTRIES_VALID);
-
   grub_dprintf ("gpt", "repairing GPT for %s successful\n", disk->name);
 
   return GRUB_ERR_NONE;
@@ -650,6 +636,12 @@ grub_gpt_update_checksums (grub_gpt_t gpt)
 {
   grub_uint32_t crc;
 
+  /* Clear status bits, require revalidation of everything.  */
+  gpt->status &= ~(GRUB_GPT_PRIMARY_HEADER_VALID |
+		   GRUB_GPT_PRIMARY_ENTRIES_VALID |
+		   GRUB_GPT_BACKUP_HEADER_VALID |
+		   GRUB_GPT_BACKUP_ENTRIES_VALID);
+
   /* Writing headers larger than our header structure are unsupported.  */
   gpt->primary.headersize =
     grub_cpu_to_le32_compile_time (sizeof (gpt->primary));
@@ -663,6 +655,18 @@ grub_gpt_update_checksums (grub_gpt_t gpt)
   grub_gpt_header_lecrc32 (&gpt->primary.crc32, &gpt->primary);
   grub_gpt_header_lecrc32 (&gpt->backup.crc32, &gpt->backup);
 
+  if (grub_gpt_check_primary (gpt))
+    return grub_error (GRUB_ERR_BUG, "Generated invalid GPT primary header");
+
+  gpt->status |= (GRUB_GPT_PRIMARY_HEADER_VALID |
+		  GRUB_GPT_PRIMARY_ENTRIES_VALID);
+
+  if (grub_gpt_check_backup (gpt))
+    return grub_error (GRUB_ERR_BUG, "Generated invalid GPT backup header");
+
+  gpt->status |= (GRUB_GPT_BACKUP_HEADER_VALID |
+		  GRUB_GPT_BACKUP_ENTRIES_VALID);
+
   return GRUB_ERR_NONE;
 }