From 6c184525320f8d40578e35e15d4965f1497d35f3 Mon Sep 17 00:00:00 2001
From: Colin Watson <cjwatson@debian.org>
Date: Wed, 19 Sep 2012 02:48:29 +0100
Subject: [PATCH] Revert incorrect off-by-one fix when embedding in MBR (LP:
 #1051154).

---
 debian/changelog                            |  1 +
 debian/patches/msdos_embed_off_by_one.patch | 30 +++++++++++++++++++++
 debian/patches/series                       |  1 +
 grub-core/partmap/msdos.c                   |  4 +--
 4 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 debian/patches/msdos_embed_off_by_one.patch

diff --git a/debian/changelog b/debian/changelog
index 3f31c3061..d979b02a2 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -3,6 +3,7 @@ grub2 (2.00-5) UNRELEASED; urgency=low
   * Backport from upstream:
     - Remove extra layer of escaping from grub_probe.
     - Add efifwsetup module to reboot into firmware setup menu.
+    - Revert incorrect off-by-one fix when embedding in MBR (LP: #1051154).
   * Switch watch file to point to ftp.gnu.org.
   * Build-depend on liblzma-dev, enabling 'grub-mkimage -C xz'.
   * Adjust /etc/grub.d/30_os-prober to detect Ubuntu's use of "recovery"
diff --git a/debian/patches/msdos_embed_off_by_one.patch b/debian/patches/msdos_embed_off_by_one.patch
new file mode 100644
index 000000000..1ccdb5f66
--- /dev/null
+++ b/debian/patches/msdos_embed_off_by_one.patch
@@ -0,0 +1,30 @@
+Description: Revert incorrect off-by-one fix when embedding in MBR
+ A 62-sector core image should fit before end == 63.
+Author: Colin Watson <cjwatson@ubuntu.com>
+Origin: upstream, http://bazaar.launchpad.net/~vcs-imports/grub/grub2-bzr/revision/4586
+Bug-Ubuntu: https://bugs.launchpad.net/bugs/1051154
+Forwarded: not-needed
+Applied-Upstream: http://bazaar.launchpad.net/~vcs-imports/grub/grub2-bzr/revision/4586
+Last-Update: 2012-09-19
+
+Index: b/grub-core/partmap/msdos.c
+===================================================================
+--- a/grub-core/partmap/msdos.c
++++ b/grub-core/partmap/msdos.c
+@@ -316,14 +316,14 @@
+ 	break;
+     }
+ 
+-  if (end >= *nsectors + 2)
++  if (end >= *nsectors + 1)
+     {
+       unsigned i, j;
+       char *embed_signature_check;
+       unsigned int orig_nsectors, avail_nsectors;
+ 
+       orig_nsectors = *nsectors;
+-      *nsectors = end - 2;
++      *nsectors = end - 1;
+       avail_nsectors = *nsectors;
+       if (*nsectors > max_nsectors)
+ 	*nsectors = max_nsectors;
diff --git a/debian/patches/series b/debian/patches/series
index ff94c4561..929cc90d6 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -21,3 +21,4 @@ install_efi_fallback.patch
 mkconfig_overescaping.patch
 efifwsetup.patch
 mkconfig_ubuntu_recovery.patch
+msdos_embed_off_by_one.patch
diff --git a/grub-core/partmap/msdos.c b/grub-core/partmap/msdos.c
index 6e54a7427..10ca3f08b 100644
--- a/grub-core/partmap/msdos.c
+++ b/grub-core/partmap/msdos.c
@@ -316,14 +316,14 @@ pc_partition_map_embed (struct grub_disk *disk, unsigned int *nsectors,
 	break;
     }
 
-  if (end >= *nsectors + 2)
+  if (end >= *nsectors + 1)
     {
       unsigned i, j;
       char *embed_signature_check;
       unsigned int orig_nsectors, avail_nsectors;
 
       orig_nsectors = *nsectors;
-      *nsectors = end - 2;
+      *nsectors = end - 1;
       avail_nsectors = *nsectors;
       if (*nsectors > max_nsectors)
 	*nsectors = max_nsectors;