From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Alexey Makhalov <amakhalov@vmware.com>

Date: Wed, 8 Jul 2020 01:44:38 +0000

Subject: [PATCH] relocator: Protect grub_relocator_alloc_chunk_align()

 max_addr against integer underflow

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>

Upstream-commit-id: 10498c8ba17

---

 grub-core/lib/i386/relocator.c        | 28 +++++++++++-----------------

 grub-core/lib/mips/relocator.c        |  6 ++----

 grub-core/lib/powerpc/relocator.c     |  6 ++----

 grub-core/lib/x86_64/efi/relocator.c  |  7 +++----

 grub-core/loader/i386/linux.c         |  5 ++---

 grub-core/loader/i386/multiboot_mbi.c |  7 +++----

 grub-core/loader/i386/pc/linux.c      |  6 ++----

 grub-core/loader/mips/linux.c         |  9 +++------

 grub-core/loader/multiboot.c          |  2 +-

 grub-core/loader/multiboot_elfxx.c    | 10 +++++-----

 grub-core/loader/multiboot_mbi2.c     | 10 +++++-----

 grub-core/loader/xnu_resume.c         |  2 +-

 include/grub/relocator.h              | 29 +++++++++++++++++++++++++++++

 13 files changed, 69 insertions(+), 58 deletions(-)

diff --git a/grub-core/lib/i386/relocator.c b/grub-core/lib/i386/relocator.c

index 71dd4f0ab..34cbe834f 100644

--- a/grub-core/lib/i386/relocator.c

+++ b/grub-core/lib/i386/relocator.c

@@ -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;

diff --git a/grub-core/lib/mips/relocator.c b/grub-core/lib/mips/relocator.c

index 9d5f49cb9..743b213e6 100644

--- a/grub-core/lib/mips/relocator.c

+++ b/grub-core/lib/mips/relocator.c

@@ -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;

diff --git a/grub-core/lib/powerpc/relocator.c b/grub-core/lib/powerpc/relocator.c

index bdf2b111b..8ffb8b686 100644

--- a/grub-core/lib/powerpc/relocator.c

+++ b/grub-core/lib/powerpc/relocator.c

@@ -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;

diff --git a/grub-core/lib/x86_64/efi/relocator.c b/grub-core/lib/x86_64/efi/relocator.c

index 3caef7a40..7d200a125 100644

--- a/grub-core/lib/x86_64/efi/relocator.c

+++ b/grub-core/lib/x86_64/efi/relocator.c

@@ -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;

diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c

index b4a30f607..191f1631e 100644

--- a/grub-core/loader/i386/linux.c

+++ b/grub-core/loader/i386/linux.c

@@ -231,9 +231,8 @@ 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);

diff --git a/grub-core/loader/i386/multiboot_mbi.c b/grub-core/loader/i386/multiboot_mbi.c

index ca85358f7..9d3466d6a 100644

--- a/grub-core/loader/i386/multiboot_mbi.c

+++ b/grub-core/loader/i386/multiboot_mbi.c

@@ -470,10 +470,9 @@ 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,

-					  GRUB_RELOCATOR_PREFERENCE_NONE, 0);

+  err = grub_relocator_alloc_chunk_align_safe (grub_multiboot_relocator, &ch,

+					       0x10000, 0xa0000, bufsize, 4,

+					       GRUB_RELOCATOR_PREFERENCE_NONE, 0);

   if (err)

     return err;

   ptrorig = get_virtual_current_address (ch);

diff --git a/grub-core/loader/i386/pc/linux.c b/grub-core/loader/i386/pc/linux.c

index 540891371..63736fae9 100644

--- a/grub-core/loader/i386/pc/linux.c

+++ b/grub-core/loader/i386/pc/linux.c

@@ -460,10 +460,8 @@ 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);

diff --git a/grub-core/loader/mips/linux.c b/grub-core/loader/mips/linux.c

index 5f383be3d..27c1db84a 100644

--- a/grub-core/loader/mips/linux.c

+++ b/grub-core/loader/mips/linux.c

@@ -434,12 +434,9 @@ 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;

diff --git a/grub-core/loader/multiboot.c b/grub-core/loader/multiboot.c

index 9a8dae556..f455e8039 100644

--- a/grub-core/loader/multiboot.c

+++ b/grub-core/loader/multiboot.c

@@ -407,7 +407,7 @@ 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)

diff --git a/grub-core/loader/multiboot_elfxx.c b/grub-core/loader/multiboot_elfxx.c

index cc6853692..f2318e0d1 100644

--- a/grub-core/loader/multiboot_elfxx.c

+++ b/grub-core/loader/multiboot_elfxx.c

@@ -109,10 +109,10 @@ 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,

-					      load_size, mld->align ? mld->align : 1,

-					      mld->preference, mld->avoid_efi_boot_services);

+      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);

       if (err)

         {

@@ -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);

diff --git a/grub-core/loader/multiboot_mbi2.c b/grub-core/loader/multiboot_mbi2.c

index 872dcd42e..3cfb47650 100644

--- a/grub-core/loader/multiboot_mbi2.c

+++ b/grub-core/loader/multiboot_mbi2.c

@@ -298,10 +298,10 @@ 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,

-						  code_size, mld.align ? mld.align : 1,

-						  mld.preference, keep_bs);

+	  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);

 	}

       else

 	err = grub_relocator_alloc_chunk_addr (grub_multiboot2_relocator,

@@ -747,7 +747,7 @@ 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,

-					  0, 0xffffffff - bufsize,

+					  0, UP_TO_TOP32 (bufsize),

 					  bufsize, MULTIBOOT_TAG_ALIGN,

 					  GRUB_RELOCATOR_PREFERENCE_NONE, 1);

   if (err)

diff --git a/grub-core/loader/xnu_resume.c b/grub-core/loader/xnu_resume.c

index 534a74438..99119558d 100644

--- a/grub-core/loader/xnu_resume.c

+++ b/grub-core/loader/xnu_resume.c

@@ -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);

diff --git a/include/grub/relocator.h b/include/grub/relocator.h

index 24d8672d2..1b3bdd92a 100644

--- a/include/grub/relocator.h

+++ b/include/grub/relocator.h

@@ -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