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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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28
grub-core/lib/i386/relocator.c
View file

@ -83,11 +83,10 @@ grub_relocator32_boot (struct grub_relocator *rel,
/* Specific memory range due to Global Descriptor Table for use by payload
that we will store in returned chunk. The address range and preference
are based on "THE LINUX/x86 BOOT PROTOCOL" specification. */
err = grub_relocator_alloc_chunk_align (rel, &ch, 0x1000,
0x9a000 - RELOCATOR_SIZEOF (32),
RELOCATOR_SIZEOF (32), 16,
GRUB_RELOCATOR_PREFERENCE_LOW,
avoid_efi_bootservices);
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, 0x1000, 0x9a000,
RELOCATOR_SIZEOF (32), 16,
GRUB_RELOCATOR_PREFERENCE_LOW,
avoid_efi_bootservices);
if (err)
return err;
@ -125,13 +124,10 @@ grub_relocator16_boot (struct grub_relocator *rel,
grub_relocator_chunk_t ch;
/* Put it higher than the byte it checks for A20 check. */
err = grub_relocator_alloc_chunk_align (rel, &ch, 0x8010,
0xa0000 - RELOCATOR_SIZEOF (16)
- GRUB_RELOCATOR16_STACK_SIZE,
RELOCATOR_SIZEOF (16)
+ GRUB_RELOCATOR16_STACK_SIZE, 16,
GRUB_RELOCATOR_PREFERENCE_NONE,
0);
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, 0x8010, 0xa0000,
RELOCATOR_SIZEOF (16) +
GRUB_RELOCATOR16_STACK_SIZE, 16,
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
return err;
@ -183,11 +179,9 @@ grub_relocator64_boot (struct grub_relocator *rel,
void *relst;
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_align (rel, &ch, min_addr,
max_addr - RELOCATOR_SIZEOF (64),
RELOCATOR_SIZEOF (64), 16,
GRUB_RELOCATOR_PREFERENCE_NONE,
0);
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, min_addr, max_addr,
RELOCATOR_SIZEOF (64), 16,
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
return err;