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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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20
grub-core/lib/i386/relocator.c
View file

@ -83,8 +83,7 @@ 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),
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, 0x1000, 0x9a000,
RELOCATOR_SIZEOF (32), 16,
GRUB_RELOCATOR_PREFERENCE_LOW,
avoid_efi_bootservices);
@ -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),
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, min_addr, max_addr,
RELOCATOR_SIZEOF (64), 16,
GRUB_RELOCATOR_PREFERENCE_NONE,
0);
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
return err;

6
grub-core/lib/mips/relocator.c
View file

@ -120,10 +120,8 @@ grub_relocator32_boot (struct grub_relocator *rel,
unsigned i;
grub_addr_t vtarget;
err = grub_relocator_alloc_chunk_align (rel, &ch, 0,
(0xffffffff - stateset_size)
+ 1, stateset_size,
sizeof (grub_uint32_t),
err = grub_relocator_alloc_chunk_align (rel, &ch, 0, UP_TO_TOP32 (stateset_size),
stateset_size, sizeof (grub_uint32_t),
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
return err;

6
grub-core/lib/powerpc/relocator.c
View file

@ -115,10 +115,8 @@ grub_relocator32_boot (struct grub_relocator *rel,
unsigned i;
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_align (rel, &ch, 0,
(0xffffffff - stateset_size)
+ 1, stateset_size,
sizeof (grub_uint32_t),
err = grub_relocator_alloc_chunk_align (rel, &ch, 0, UP_TO_TOP32 (stateset_size),
stateset_size, sizeof (grub_uint32_t),
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
return err;

3
grub-core/lib/x86_64/efi/relocator.c
View file

@ -50,8 +50,7 @@ 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),
err = grub_relocator_alloc_chunk_align_safe (rel, &ch, 0, 0x100000000,
RELOCATOR_SIZEOF (64_efi), 16,
GRUB_RELOCATOR_PREFERENCE_NONE, 1);
if (err)

5
grub-core/loader/i386/linux.c
View file

@ -181,9 +181,8 @@ allocate_pages (grub_size_t prot_size, grub_size_t *align,
for (; err && *align + 1 > min_align; (*align)--)
{
grub_errno = GRUB_ERR_NONE;
err = grub_relocator_alloc_chunk_align (relocator, &ch,
0x1000000,
0xffffffff & ~prot_size,
err = grub_relocator_alloc_chunk_align (relocator, &ch, 0x1000000,
UP_TO_TOP32 (prot_size),
prot_size, 1 << *align,
GRUB_RELOCATOR_PREFERENCE_LOW,
1);

5
grub-core/loader/i386/multiboot_mbi.c
View file

@ -466,9 +466,8 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
bufsize = grub_multiboot_get_mbi_size ();
err = grub_relocator_alloc_chunk_align (grub_multiboot_relocator, &ch,
0x10000, 0xa0000 - bufsize,
bufsize, 4,
err = grub_relocator_alloc_chunk_align_safe (grub_multiboot_relocator, &ch,
0x10000, 0xa0000, bufsize, 4,
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
return err;

6
grub-core/loader/i386/pc/linux.c
View file

@ -453,10 +453,8 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
{
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_align (relocator, &ch,
addr_min, addr_max - size,
size, 0x1000,
GRUB_RELOCATOR_PREFERENCE_HIGH, 0);
err = grub_relocator_alloc_chunk_align_safe (relocator, &ch, addr_min, addr_max, size,
0x1000, GRUB_RELOCATOR_PREFERENCE_HIGH, 0);
if (err)
return err;
initrd_chunk = get_virtual_current_address (ch);

9
grub-core/loader/mips/linux.c
View file

@ -442,12 +442,9 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
{
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_align (relocator, &ch,
(target_addr & 0x1fffffff)
+ linux_size + 0x10000,
(0x10000000 - size),
size, 0x10000,
GRUB_RELOCATOR_PREFERENCE_NONE, 0);
err = grub_relocator_alloc_chunk_align_safe (relocator, &ch, (target_addr & 0x1fffffff) +
linux_size + 0x10000, 0x10000000, size,
0x10000, GRUB_RELOCATOR_PREFERENCE_NONE, 0);
if (err)
goto fail;

2
grub-core/loader/multiboot.c
View file

@ -403,7 +403,7 @@ grub_cmd_module (grub_command_t cmd __attribute__ ((unused)),
{
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_align (GRUB_MULTIBOOT (relocator), &ch,
lowest_addr, (0xffffffff - size) + 1,
lowest_addr, UP_TO_TOP32 (size),
size, MULTIBOOT_MOD_ALIGN,
GRUB_RELOCATOR_PREFERENCE_NONE, 1);
if (err)

6
grub-core/loader/multiboot_elfxx.c
View file

@ -109,8 +109,8 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld)
if (load_size > mld->max_addr || mld->min_addr > mld->max_addr - load_size)
return grub_error (GRUB_ERR_BAD_OS, "invalid min/max address and/or load size");
err = grub_relocator_alloc_chunk_align (GRUB_MULTIBOOT (relocator), &ch,
mld->min_addr, mld->max_addr - load_size,
err = grub_relocator_alloc_chunk_align_safe (GRUB_MULTIBOOT (relocator), &ch,
mld->min_addr, mld->max_addr,
load_size, mld->align ? mld->align : 1,
mld->preference, mld->avoid_efi_boot_services);
@ -256,7 +256,7 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld)
continue;
err = grub_relocator_alloc_chunk_align (GRUB_MULTIBOOT (relocator), &ch, 0,
(0xffffffff - sh->sh_size) + 1,
UP_TO_TOP32 (sh->sh_size),
sh->sh_size, sh->sh_addralign,
GRUB_RELOCATOR_PREFERENCE_NONE,
mld->avoid_efi_boot_services);

6
grub-core/loader/multiboot_mbi2.c
View file

@ -301,8 +301,8 @@ grub_multiboot2_load (grub_file_t file, const char *filename)
return grub_error (GRUB_ERR_BAD_OS, "invalid min/max address and/or load size");
}
err = grub_relocator_alloc_chunk_align (grub_multiboot2_relocator, &ch,
mld.min_addr, mld.max_addr - code_size,
err = grub_relocator_alloc_chunk_align_safe (grub_multiboot2_relocator, &ch,
mld.min_addr, mld.max_addr,
code_size, mld.align ? mld.align : 1,
mld.preference, keep_bs);
}
@ -714,7 +714,7 @@ grub_multiboot2_make_mbi (grub_uint32_t *target)
COMPILE_TIME_ASSERT (MULTIBOOT_TAG_ALIGN % sizeof (grub_properly_aligned_t) == 0);
err = grub_relocator_alloc_chunk_align (grub_multiboot2_relocator, &ch,
MBI_MIN_ADDR, 0xffffffff - bufsize,
MBI_MIN_ADDR, UP_TO_TOP32 (bufsize),
bufsize, MULTIBOOT_TAG_ALIGN,
GRUB_RELOCATOR_PREFERENCE_NONE, 1);
if (err)

2
grub-core/loader/xnu_resume.c
View file

@ -129,7 +129,7 @@ grub_xnu_resume (char *imagename)
{
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_align (grub_xnu_relocator, &ch, 0,
(0xffffffff - hibhead.image_size) + 1,
UP_TO_TOP32 (hibhead.image_size),
hibhead.image_size,
GRUB_XNU_PAGESIZE,
GRUB_RELOCATOR_PREFERENCE_NONE, 0);

29
include/grub/relocator.h
View file

@ -49,6 +49,35 @@ grub_relocator_alloc_chunk_align (struct grub_relocator *rel,
int preference,
int avoid_efi_boot_services);
/*
* Wrapper for grub_relocator_alloc_chunk_align() with purpose of
* protecting against integer underflow.
*
* Compare to its callee, max_addr has different meaning here.
* It covers entire chunk and not just start address of the chunk.
*/
static inline grub_err_t
grub_relocator_alloc_chunk_align_safe (struct grub_relocator *rel,
grub_relocator_chunk_t *out,
grub_phys_addr_t min_addr,
grub_phys_addr_t max_addr,
grub_size_t size, grub_size_t align,
int preference,
int avoid_efi_boot_services)
{
/* Sanity check and ensure following equation (max_addr - size) is safe. */
if (max_addr < size || (max_addr - size) < min_addr)
return GRUB_ERR_OUT_OF_RANGE;
return grub_relocator_alloc_chunk_align (rel, out, min_addr,
max_addr - size,
size, align, preference,
avoid_efi_boot_services);
}
/* Top 32-bit address minus s bytes and plus 1 byte. */
#define UP_TO_TOP32(s) ((~(s) & 0xffffffff) + 1)
#define GRUB_RELOCATOR_PREFERENCE_NONE 0
#define GRUB_RELOCATOR_PREFERENCE_LOW 1
#define GRUB_RELOCATOR_PREFERENCE_HIGH 2