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relocator: Protect grub_relocator_alloc_chunk_align() max_addr against integer underflow

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This commit introduces integer underflow mitigation in max_addr calculation
in grub_relocator_alloc_chunk_align() invocation.

It consists of 2 fixes:
  1. Introduced grub_relocator_alloc_chunk_align_safe() wrapper function to perform
     sanity check for min/max and size values, and to make safe invocation of
     grub_relocator_alloc_chunk_align() with validated max_addr value. Replace all
     invocations such as grub_relocator_alloc_chunk_align(..., min_addr, max_addr - size, size, ...)
     by grub_relocator_alloc_chunk_align_safe(..., min_addr, max_addr, size, ...).
  2. Introduced UP_TO_TOP32(s) macro for the cases where max_addr is 32-bit top
     address (0xffffffff - size + 1) or similar.

Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Alexey Makhalov 2020-07-08 01:44:38 +00:00 • committed by Daniel Kiper
parent caea56d1f8
commit 61ff5602fe
13 changed files with 69 additions and 58 deletions
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7
grub-core/lib/x86_64/efi/relocator.c
View file

@ -50,10 +50,9 @@ grub_relocator64_efi_boot (struct grub_relocator *rel,
* 64-bit relocator code may live above 4 GiB quite well.
* However, I do not want ask for problems. Just in case.
*/
err = grub_relocator_alloc_chunk_align (rel, &ch, 0,
0x100000000 - RELOCATOR_SIZEOF (64_efi),
RELOCATOR_SIZEOF (64_efi), 16,
GRUB_RELOCATOR_PREFERENCE_NONE, 1);
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, 0, 0x100000000,
RELOCATOR_SIZEOF (64_efi), 16,
GRUB_RELOCATOR_PREFERENCE_NONE, 1);
if (err)
return err;