1From 06aa91f79f902752cb7e5d22ac0ea8e13bffd056 Mon Sep 17 00:00:00 2001
2From: Alexey Makhalov <amakhalov@vmware.com>
3Date: Fri, 17 Jul 2020 05:17:26 +0000
4Subject: [PATCH] relocator: Fix grub_relocator_alloc_chunk_align() top
5 memory allocation
6MIME-Version: 1.0
7Content-Type: text/plain; charset=UTF-8
8Content-Transfer-Encoding: 8bit
9
10Current implementation of grub_relocator_alloc_chunk_align()
11does not allow allocation of the top byte.
12
13Assuming input args are:
14  max_addr = 0xfffff000;
15  size = 0x1000;
16
17And this is valid. But following overflow protection will
18unnecessarily move max_addr one byte down (to 0xffffefff):
19  if (max_addr > ~size)
20    max_addr = ~size;
21
22~size + 1 will fix the situation. In addition, check size
23for non zero to do not zero max_addr.
24
25Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
26Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
27Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
28---
29 grub-core/lib/relocator.c | 4 ++--
30 1 file changed, 2 insertions(+), 2 deletions(-)
31
32diff --git a/grub-core/lib/relocator.c b/grub-core/lib/relocator.c
33index 5847aac36..f2c1944c2 100644
34--- a/grub-core/lib/relocator.c
35+++ b/grub-core/lib/relocator.c
36@@ -1386,8 +1386,8 @@ grub_relocator_alloc_chunk_align (struct grub_relocator *rel,
37   };
38   grub_addr_t min_addr2 = 0, max_addr2;
39
40-  if (max_addr > ~size)
41-    max_addr = ~size;
42+  if (size && (max_addr > ~size))
43+    max_addr = ~size + 1;
44
45 #ifdef GRUB_MACHINE_PCBIOS
46   if (min_addr < 0x1000)
47--
482.26.2
49
50