Commit f9d230e8 authored by Borislav Petkov's avatar Borislav Petkov
Browse files

x86/boot: Correct RSDP parsing with 32-bit EFI 



Guenter Roeck reported triple faults of a 64-bit VM using a 32-bit OVMF
EFI image. After some singlestepping of the image in gdb, it turned out
that some of the EFI config tables were at bogus addresses. Which, as
Ard pointed out, results from using the wrong efi_config_table typedef.

So switch all EFI table pointers to unsigned longs and convert them to
the proper typedef only when accessing them. This way, the proper table
type is being used.

Shorten variable names, while at it.

Fixes: 33f0df8d ("x86/boot: Search for RSDP in the EFI tables")
Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Tested-by: default avatarChao Fan <fanc.fnst@cn.fujitsu.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: bhe@redhat.com
Cc: caoj.fnst@cn.fujitsu.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: indou.takao@jp.fujitsu.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: kasong@redhat.com
Cc: Kees Cook <keescook@chromium.org>
Cc: msys.mizuma@gmail.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190208190248.GA10854@roeck-us.net
parent ccec81e4

arch/x86/boot/compressed/acpi.c

+31 −19
Original line number Original line Diff line number Diff line
@@ -50,7 +50,8 @@ static acpi_physical_address efi_get_rsdp_addr(void) 
	acpi_physical_address rsdp_addr = 0;

	acpi_physical_address rsdp_addr = 0;





#ifdef CONFIG_EFI

#ifdef CONFIG_EFI

	efi_system_table_t *systab;

	unsigned long systab, systab_tables, config_tables;

	unsigned int nr_tables;

	struct efi_info *ei;

	struct efi_info *ei;

	bool efi_64;

	bool efi_64;

	int size, i;

	int size, i;
@@ -70,46 +71,57 @@ static acpi_physical_address efi_get_rsdp_addr(void) 




	/* Get systab from boot params. */

	/* Get systab from boot params. */

#ifdef CONFIG_X86_64

#ifdef CONFIG_X86_64

	systab = (efi_system_table_t *)(ei->efi_systab | ((__u64)ei->efi_systab_hi<<32));

	systab = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);

#else

#else

	if (ei->efi_systab_hi || ei->efi_memmap_hi) {

	if (ei->efi_systab_hi || ei->efi_memmap_hi) {

		debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n");

		debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n");

		return 0;

		return 0;

	}

	}

	systab = (efi_system_table_t *)ei->efi_systab;

	systab = ei->efi_systab;

#endif

#endif

	if (!systab)

	if (!systab)

		error("EFI system table not found.");

		error("EFI system table not found.");





	/*

	/* Handle EFI bitness properly */

	 * Get EFI tables from systab.

	if (efi_64) {

	 */

		efi_system_table_64_t *stbl = (efi_system_table_64_t *)systab;

	size = efi_64 ? sizeof(efi_config_table_64_t) :



			sizeof(efi_config_table_32_t);

		config_tables	= stbl->tables;

		nr_tables	= stbl->nr_tables;

		size		= sizeof(efi_config_table_64_t);

	} else {

		efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab;





	for (i = 0; i < systab->nr_tables; i++) {

		config_tables	= stbl->tables;

		nr_tables	= stbl->nr_tables;

		size		= sizeof(efi_config_table_32_t);

	}



	if (!config_tables)

		error("EFI config tables not found.");



	/* Get EFI tables from systab. */

	for (i = 0; i < nr_tables; i++) {

		acpi_physical_address table;

		acpi_physical_address table;

		void *config_tables;

		efi_guid_t guid;

		efi_guid_t guid;





		config_tables = (void *)(systab->tables + size * i);

		config_tables += size;



		if (efi_64) {

		if (efi_64) {

			efi_config_table_64_t *tmp_table;

			efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables;





			tmp_table = config_tables;

			guid  = tbl->guid;

			guid = tmp_table->guid;

			table = tbl->table;

			table = tmp_table->table;





			if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) {

			if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) {

				debug_putstr("Error getting RSDP address: EFI config table located above 4GB.\n");

				debug_putstr("Error getting RSDP address: EFI config table located above 4GB.\n");

				return 0;

				return 0;

			}

			}

		} else {

		} else {

			efi_config_table_32_t *tmp_table;

			efi_config_table_32_t *tbl = (efi_config_table_32_t *)config_tables;





			tmp_table = config_tables;

			guid  = tbl->guid;

			guid = tmp_table->guid;

			table = tbl->table;

			table = tmp_table->table;

		}

		}





		if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))

		if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))

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