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relocator: Fix grub_relocator_alloc_chunk_align() top memory allocation 

Current implementation of grub_relocator_alloc_chunk_align()
does not allow allocation of the top byte.

Assuming input args are:
  max_addr = 0xfffff000;
  size = 0x1000;

And this is valid. But following overflow protection will
unnecessarily move max_addr one byte down (to 0xffffefff):
  if (max_addr > ~size)
    max_addr = ~size;

~size + 1 will fix the situation. In addition, check size
for non zero to do not zero max_addr.

Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Alexey Makhalov 2020-07-17 05:17:26 +00:00 committed by Daniel Kiper
parent 426f57383d
commit 07e5b79e22
1 changed files with 2 additions and 2 deletions
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4
grub-core/lib/relocator.c
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@ -1386,8 +1386,8 @@ grub_relocator_alloc_chunk_align (struct grub_relocator *rel,
};
grub_addr_t min_addr2 = 0, max_addr2;
if (max_addr > ~size)
max_addr = ~size;
if (size && (max_addr > ~size))
max_addr = ~size + 1;
#ifdef GRUB_MACHINE_PCBIOS
if (min_addr < 0x1000)