grub/grub-core/loader/mips/linux.c
Alexey Makhalov 61ff5602fe 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>
2020-07-29 16:55:48 +02:00

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/* linux.c - boot Linux */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2003,2004,2005,2007,2009,2010 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/elf.h>
#include <grub/elfload.h>
#include <grub/loader.h>
#include <grub/dl.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/command.h>
#include <grub/mips/relocator.h>
#include <grub/memory.h>
#include <grub/i18n.h>
#include <grub/lib/cmdline.h>
#include <grub/linux.h>
GRUB_MOD_LICENSE ("GPLv3+");
#pragma GCC diagnostic ignored "-Wcast-align"
/* For frequencies. */
#include <grub/machine/time.h>
#ifdef GRUB_MACHINE_MIPS_LOONGSON
#include <grub/pci.h>
#include <grub/machine/kernel.h>
const char loongson_machtypes[][60] =
{
[GRUB_ARCH_MACHINE_YEELOONG] = "machtype=lemote-yeeloong-2f-8.9inches",
[GRUB_ARCH_MACHINE_FULOONG2F] = "machtype=lemote-fuloong-2f-box",
[GRUB_ARCH_MACHINE_FULOONG2E] = "machtype=lemote-fuloong-2e-unknown"
};
#endif
static grub_dl_t my_mod;
static int loaded;
static grub_size_t linux_size;
static struct grub_relocator *relocator;
static grub_uint8_t *playground;
static grub_addr_t target_addr, entry_addr;
#ifdef GRUB_MACHINE_MIPS_QEMU_MIPS
static char *params;
#else
static int linux_argc;
static grub_off_t argv_off;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
static grub_off_t envp_off;
#endif
static grub_off_t rd_addr_arg_off, rd_size_arg_off;
#endif
static int initrd_loaded = 0;
static grub_err_t
grub_linux_boot (void)
{
struct grub_relocator32_state state;
grub_memset (&state, 0, sizeof (state));
/* Boot the kernel. */
state.gpr[1] = entry_addr;
#ifdef GRUB_MACHINE_MIPS_QEMU_MIPS
{
grub_err_t err;
grub_relocator_chunk_t ch;
grub_uint32_t *memsize;
grub_uint32_t *magic;
char *str;
err = grub_relocator_alloc_chunk_addr (relocator, &ch,
((16 << 20) - 264),
grub_strlen (params) + 1 + 8);
if (err)
return err;
memsize = get_virtual_current_address (ch);
magic = memsize + 1;
*memsize = grub_mmap_get_lower ();
*magic = 0x12345678;
str = (char *) (magic + 1);
grub_strcpy (str, params);
}
#endif
#ifndef GRUB_MACHINE_MIPS_QEMU_MIPS
state.gpr[4] = linux_argc;
state.gpr[5] = target_addr + argv_off;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
state.gpr[6] = target_addr + envp_off;
#else
state.gpr[6] = 0;
#endif
state.gpr[7] = 0;
#endif
state.jumpreg = 1;
grub_relocator32_boot (relocator, state);
return GRUB_ERR_NONE;
}
static grub_err_t
grub_linux_unload (void)
{
grub_relocator_unload (relocator);
grub_dl_unref (my_mod);
#ifdef GRUB_MACHINE_MIPS_QEMU_MIPS
grub_free (params);
params = 0;
#endif
loaded = 0;
return GRUB_ERR_NONE;
}
static grub_err_t
grub_linux_load32 (grub_elf_t elf, const char *filename,
void **extra_mem, grub_size_t extra_size)
{
Elf32_Addr base;
int extraoff;
grub_err_t err;
/* Linux's entry point incorrectly contains a virtual address. */
entry_addr = elf->ehdr.ehdr32.e_entry;
linux_size = grub_elf32_size (elf, &base, 0);
if (linux_size == 0)
return grub_errno;
target_addr = base;
/* Pad it; the kernel scribbles over memory beyond its load address. */
linux_size += 0x100000;
linux_size = ALIGN_UP (base + linux_size, 4) - base;
extraoff = linux_size;
linux_size += extra_size;
relocator = grub_relocator_new ();
if (!relocator)
return grub_errno;
{
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_addr (relocator, &ch,
target_addr & 0x1fffffff,
linux_size);
if (err)
return err;
playground = get_virtual_current_address (ch);
}
*extra_mem = playground + extraoff;
/* Now load the segments into the area we claimed. */
return grub_elf32_load (elf, filename, playground - base, GRUB_ELF_LOAD_FLAGS_NONE, 0, 0);
}
static grub_err_t
grub_linux_load64 (grub_elf_t elf, const char *filename,
void **extra_mem, grub_size_t extra_size)
{
Elf64_Addr base;
int extraoff;
grub_err_t err;
/* Linux's entry point incorrectly contains a virtual address. */
entry_addr = elf->ehdr.ehdr64.e_entry;
linux_size = grub_elf64_size (elf, &base, 0);
if (linux_size == 0)
return grub_errno;
target_addr = base;
/* Pad it; the kernel scribbles over memory beyond its load address. */
linux_size += 0x100000;
linux_size = ALIGN_UP (base + linux_size, 4) - base;
extraoff = linux_size;
linux_size += extra_size;
relocator = grub_relocator_new ();
if (!relocator)
return grub_errno;
{
grub_relocator_chunk_t ch;
err = grub_relocator_alloc_chunk_addr (relocator, &ch,
target_addr & 0x1fffffff,
linux_size);
if (err)
return err;
playground = get_virtual_current_address (ch);
}
*extra_mem = playground + extraoff;
/* Now load the segments into the area we claimed. */
return grub_elf64_load (elf, filename, playground - base, GRUB_ELF_LOAD_FLAGS_NONE, 0, 0);
}
static grub_err_t
grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
int argc, char *argv[])
{
grub_elf_t elf = 0;
int size;
void *extra = NULL;
#ifndef GRUB_MACHINE_MIPS_QEMU_MIPS
int i;
grub_uint32_t *linux_argv;
char *linux_args;
#endif
grub_err_t err;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
char *linux_envs;
grub_uint32_t *linux_envp;
#endif
if (argc == 0)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
elf = grub_elf_open (argv[0], GRUB_FILE_TYPE_LINUX_KERNEL);
if (! elf)
return grub_errno;
if (elf->ehdr.ehdr32.e_type != ET_EXEC)
{
grub_elf_close (elf);
return grub_error (GRUB_ERR_UNKNOWN_OS,
N_("this ELF file is not of the right type"));
}
/* Release the previously used memory. */
grub_loader_unset ();
loaded = 0;
#ifdef GRUB_MACHINE_MIPS_QEMU_MIPS
size = 0;
#else
/* For arguments. */
linux_argc = argc;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
linux_argc++;
#endif
/* Main arguments. */
size = (linux_argc) * sizeof (grub_uint32_t);
/* Initrd address and size. */
size += 2 * sizeof (grub_uint32_t);
/* NULL terminator. */
size += sizeof (grub_uint32_t);
/* First argument is always "a0". */
size += ALIGN_UP (sizeof ("a0"), 4);
/* Normal arguments. */
for (i = 1; i < argc; i++)
size += ALIGN_UP (grub_strlen (argv[i]) + 1, 4);
#ifdef GRUB_MACHINE_MIPS_LOONGSON
size += ALIGN_UP (sizeof (loongson_machtypes[0]), 4);
#endif
/* rd arguments. */
size += ALIGN_UP (sizeof ("rd_start=0xXXXXXXXXXXXXXXXX"), 4);
size += ALIGN_UP (sizeof ("rd_size=0xXXXXXXXXXXXXXXXX"), 4);
/* For the environment. */
size += sizeof (grub_uint32_t);
size += 4 * sizeof (grub_uint32_t);
size += ALIGN_UP (sizeof ("memsize=XXXXXXXXXXXXXXXXXXXX"), 4)
+ ALIGN_UP (sizeof ("highmemsize=XXXXXXXXXXXXXXXXXXXX"), 4)
+ ALIGN_UP (sizeof ("busclock=XXXXXXXXXX"), 4)
+ ALIGN_UP (sizeof ("cpuclock=XXXXXXXXXX"), 4);
#endif
if (grub_elf_is_elf32 (elf))
err = grub_linux_load32 (elf, argv[0], &extra, size);
else
if (grub_elf_is_elf64 (elf))
err = grub_linux_load64 (elf, argv[0], &extra, size);
else
err = grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-dependent ELF magic"));
grub_elf_close (elf);
if (err)
return err;
#ifdef GRUB_MACHINE_MIPS_QEMU_MIPS
/* Create kernel command line. */
size = grub_loader_cmdline_size(argc, argv);
params = grub_malloc (size + sizeof (LINUX_IMAGE));
if (! params)
{
grub_linux_unload ();
return grub_errno;
}
grub_memcpy (params, LINUX_IMAGE, sizeof (LINUX_IMAGE));
grub_create_loader_cmdline (argc, argv, params + sizeof (LINUX_IMAGE) - 1,
size, GRUB_VERIFY_KERNEL_CMDLINE);
#else
linux_argv = extra;
argv_off = (grub_uint8_t *) linux_argv - (grub_uint8_t *) playground;
extra = linux_argv + (linux_argc + 1 + 2);
linux_args = extra;
grub_memcpy (linux_args, "a0", sizeof ("a0"));
*linux_argv = (grub_uint8_t *) linux_args - (grub_uint8_t *) playground
+ target_addr;
linux_argv++;
linux_args += ALIGN_UP (sizeof ("a0"), 4);
char *params = linux_args;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
{
unsigned mtype = grub_arch_machine;
if (mtype >= ARRAY_SIZE (loongson_machtypes))
mtype = 0;
/* In Loongson platform, it is the responsibility of the bootloader/firmware
to supply the OS kernel with machine type information. */
grub_memcpy (linux_args, loongson_machtypes[mtype],
sizeof (loongson_machtypes[mtype]));
*linux_argv = (grub_uint8_t *) linux_args - (grub_uint8_t *) playground
+ target_addr;
linux_argv++;
linux_args += ALIGN_UP (sizeof (loongson_machtypes[mtype]), 4);
}
#endif
for (i = 1; i < argc; i++)
{
grub_memcpy (linux_args, argv[i], grub_strlen (argv[i]) + 1);
*linux_argv = (grub_uint8_t *) linux_args - (grub_uint8_t *) playground
+ target_addr;
linux_argv++;
linux_args += ALIGN_UP (grub_strlen (argv[i]) + 1, 4);
}
*linux_args = '\0';
err = grub_verify_string (params, GRUB_VERIFY_KERNEL_CMDLINE);
if (err)
return err;
/* Reserve space for rd arguments. */
rd_addr_arg_off = (grub_uint8_t *) linux_args - (grub_uint8_t *) playground;
linux_args += ALIGN_UP (sizeof ("rd_start=0xXXXXXXXXXXXXXXXX"), 4);
*linux_argv = 0;
linux_argv++;
rd_size_arg_off = (grub_uint8_t *) linux_args - (grub_uint8_t *) playground;
linux_args += ALIGN_UP (sizeof ("rd_size=0xXXXXXXXXXXXXXXXX"), 4);
*linux_argv = 0;
linux_argv++;
*linux_argv = 0;
extra = linux_args;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
linux_envp = extra;
envp_off = (grub_uint8_t *) linux_envp - (grub_uint8_t *) playground;
linux_envs = (char *) (linux_envp + 5);
grub_snprintf (linux_envs, sizeof ("memsize=XXXXXXXXXXXXXXXXXXXX"),
"memsize=%lld",
(unsigned long long) grub_mmap_get_lower () >> 20);
linux_envp[0] = (grub_uint8_t *) linux_envs - (grub_uint8_t *) playground
+ target_addr;
linux_envs += ALIGN_UP (grub_strlen (linux_envs) + 1, 4);
grub_snprintf (linux_envs, sizeof ("highmemsize=XXXXXXXXXXXXXXXXXXXX"),
"highmemsize=%lld",
(unsigned long long) grub_mmap_get_upper () >> 20);
linux_envp[1] = (grub_uint8_t *) linux_envs - (grub_uint8_t *) playground
+ target_addr;
linux_envs += ALIGN_UP (grub_strlen (linux_envs) + 1, 4);
grub_snprintf (linux_envs, sizeof ("busclock=XXXXXXXXXX"),
"busclock=%d", grub_arch_busclock);
linux_envp[2] = (grub_uint8_t *) linux_envs - (grub_uint8_t *) playground
+ target_addr;
linux_envs += ALIGN_UP (grub_strlen (linux_envs) + 1, 4);
grub_snprintf (linux_envs, sizeof ("cpuclock=XXXXXXXXXX"),
"cpuclock=%d", grub_arch_cpuclock);
linux_envp[3] = (grub_uint8_t *) linux_envs - (grub_uint8_t *) playground
+ target_addr;
linux_envs += ALIGN_UP (grub_strlen (linux_envs) + 1, 4);
linux_envp[4] = 0;
#endif
#endif
grub_loader_set (grub_linux_boot, grub_linux_unload, 1);
initrd_loaded = 0;
loaded = 1;
grub_dl_ref (my_mod);
return GRUB_ERR_NONE;
}
static grub_err_t
grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
int argc, char *argv[])
{
grub_size_t size = 0;
void *initrd_src;
grub_addr_t initrd_dest;
grub_err_t err;
struct grub_linux_initrd_context initrd_ctx = { 0, 0, 0 };
if (argc == 0)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
if (!loaded)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("you need to load the kernel first"));
if (initrd_loaded)
return grub_error (GRUB_ERR_BAD_ARGUMENT, "only one initrd command can be issued.");
if (grub_initrd_init (argc, argv, &initrd_ctx))
goto fail;
size = grub_get_initrd_size (&initrd_ctx);
{
grub_relocator_chunk_t ch;
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;
initrd_src = get_virtual_current_address (ch);
initrd_dest = get_physical_target_address (ch) | 0x80000000;
}
if (grub_initrd_load (&initrd_ctx, argv, initrd_src))
goto fail;
#ifdef GRUB_MACHINE_MIPS_QEMU_MIPS
{
char *tmp;
tmp = grub_xasprintf ("%s rd_start=0x%" PRIxGRUB_ADDR
" rd_size=0x%" PRIxGRUB_ADDR, params,
initrd_dest, size);
if (!tmp)
goto fail;
grub_free (params);
params = tmp;
}
#else
grub_snprintf ((char *) playground + rd_addr_arg_off,
sizeof ("rd_start=0xXXXXXXXXXXXXXXXX"), "rd_start=0x%llx",
(unsigned long long) initrd_dest);
((grub_uint32_t *) (playground + argv_off))[linux_argc]
= target_addr + rd_addr_arg_off;
linux_argc++;
grub_snprintf ((char *) playground + rd_size_arg_off,
sizeof ("rd_size=0xXXXXXXXXXXXXXXXXX"), "rd_size=0x%llx",
(unsigned long long) size);
((grub_uint32_t *) (playground + argv_off))[linux_argc]
= target_addr + rd_size_arg_off;
linux_argc++;
#endif
initrd_loaded = 1;
fail:
grub_initrd_close (&initrd_ctx);
return grub_errno;
}
static grub_command_t cmd_linux, cmd_initrd;
GRUB_MOD_INIT(linux)
{
cmd_linux = grub_register_command ("linux", grub_cmd_linux,
0, N_("Load Linux."));
cmd_initrd = grub_register_command ("initrd", grub_cmd_initrd,
0, N_("Load initrd."));
my_mod = mod;
}
GRUB_MOD_FINI(linux)
{
grub_unregister_command (cmd_linux);
grub_unregister_command (cmd_initrd);
}