Re: [PATCH 1/1] ACPI: fix acpi table use after free

George Kennedy
2021-03-17T22:29:41Z

On 3/17/2021 4:14 PM, Rafael J. Wysocki wrote:
> On Monday, March 15, 2021 5:19:29 PM CET Rafael J. Wysocki wrote:
>> On Sun, Mar 14, 2021 at 8:00 PM Mike Rapoport <rppt@linux.ibm.com> wrote:
>>> On Thu, Mar 11, 2021 at 04:36:31PM +0100, Rafael J. Wysocki wrote:
>>>> On Wed, Mar 10, 2021 at 8:47 PM David Hildenbrand <david@redhat.com> wrote:
>>>>>> There is some care that should be taken to make sure we get the order
>>>>>> right, but I don't see a fundamental issue here.
>>>> Me neither.
>>>>
>>>>>> If I understand correctly, Rafael's concern is about changing the parts of
>>>>>> ACPICA that should be OS agnostic, so I think we just need another place to
>>>>>> call memblock_reserve() rather than acpi_tb_install_table_with_override().
>>>> Something like this.
>>>>
>>>> There is also the problem that memblock_reserve() needs to be called
>>>> for all of the tables early enough, which will require some reordering
>>>> of the early init code.
>>>>
>>>>>> Since the reservation should be done early in x86::setup_arch() (and
>>>>>> probably in arm64::setup_arch()) we might just have a function that parses
>>>>>> table headers and reserves them, similarly to how we parse the tables
>>>>>> during KASLR setup.
>>>> Right.
>>> I've looked at it a bit more and we do something like the patch below that
>>> nearly duplicates acpi_tb_parse_root_table() which is not very nice.
>> It looks to me that the code need not be duplicated (see below).
>>
>>> Besides, reserving ACPI tables early and then calling acpi_table_init()
>>> (and acpi_tb_parse_root_table() again would mean doing the dance with
>>> early_memremap() twice for no good reason.
>> That'd be simply inefficient which is kind of acceptable to me to start with.
>>
>> And I changing the ACPICA code can be avoided at least initially, it
>> by itself would be a good enough reason.
>>
>>> I believe the most effective way to deal with this would be to have a
>>> function that does parsing, reservation and installs the tables supplied by
>>> the firmware which can be called really early and then another function
>>> that overrides tables if needed a some later point.
>> I agree that this should be the direction to go into.
> So maybe something like the patch below?

Do you want me to try it out in the failing setup?

George
>
> I'm not sure if acpi_boot_table_prepare() gets called early enough, though.
>
> Also this still may not play well with initrd-based table overrides. Erik, do
> you have any insights here?
>
> And ia64 needs to be updated too.
>
> ---
> arch/x86/kernel/acpi/boot.c | 12 +++++++++---
> arch/x86/kernel/setup.c | 3 +++
> drivers/acpi/tables.c | 24 +++++++++++++++++++++---
> include/linux/acpi.h | 9 +++++++--
> 4 files changed, 40 insertions(+), 8 deletions(-)
>
> Index: linux-pm/arch/x86/kernel/acpi/boot.c
> ===================================================================
> --- linux-pm.orig/arch/x86/kernel/acpi/boot.c
> +++ linux-pm/arch/x86/kernel/acpi/boot.c
> @@ -1541,7 +1541,7 @@ static const struct dmi_system_id acpi_d
> * ...
> */
>
> -void __init acpi_boot_table_init(void)
> +void __init acpi_boot_table_prepare(void)
> {
> dmi_check_system(acpi_dmi_table);
>
> @@ -1554,10 +1554,16 @@ void __init acpi_boot_table_init(void)
> /*
> * Initialize the ACPI boot-time table parser.
> */
> - if (acpi_table_init()) {
> + if (acpi_table_prepare())
> disable_acpi();
> +}
> +
> +void __init acpi_boot_table_init(void)
> +{
> + if (acpi_disabled)
> return;
> - }
> +
> + acpi_table_init();
>
> acpi_table_parse(ACPI_SIG_BOOT, acpi_parse_sbf);
>
> Index: linux-pm/arch/x86/kernel/setup.c
> ===================================================================
> --- linux-pm.orig/arch/x86/kernel/setup.c
> +++ linux-pm/arch/x86/kernel/setup.c
> @@ -1070,6 +1070,9 @@ void __init setup_arch(char **cmdline_p)
> /* preallocate 4k for mptable mpc */
> e820__memblock_alloc_reserved_mpc_new();
>
> + /* Look for ACPI tables and reserve memory occupied by them. */
> + acpi_boot_table_prepare();
> +
> #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
> setup_bios_corruption_check();
> #endif
> Index: linux-pm/include/linux/acpi.h
> ===================================================================
> --- linux-pm.orig/include/linux/acpi.h
> +++ linux-pm/include/linux/acpi.h
> @@ -222,11 +222,13 @@ void __iomem *__acpi_map_table(unsigned
> void __acpi_unmap_table(void __iomem *map, unsigned long size);
> int early_acpi_boot_init(void);
> int acpi_boot_init (void);
> +void acpi_boot_table_prepare (void);
> void acpi_boot_table_init (void);
> int acpi_mps_check (void);
> int acpi_numa_init (void);
>
> -int acpi_table_init (void);
> +int acpi_table_prepare (void);
> +void acpi_table_init (void);
> int acpi_table_parse(char *id, acpi_tbl_table_handler handler);
> int __init acpi_table_parse_entries(char *id, unsigned long table_size,
> int entry_id,
> @@ -814,9 +816,12 @@ static inline int acpi_boot_init(void)
> return 0;
> }
>
> +static inline void acpi_boot_table_prepare(void)
> +{
> +}
> +
> static inline void acpi_boot_table_init(void)
> {
> - return;
> }
>
> static inline int acpi_mps_check(void)
> Index: linux-pm/drivers/acpi/tables.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/tables.c
> +++ linux-pm/drivers/acpi/tables.c
> @@ -788,9 +788,10 @@ acpi_status acpi_os_table_override(struc
> * result: sdt_entry[] is initialized
> */
>
> -int __init acpi_table_init(void)
> +int __init acpi_table_prepare(void)
> {
> acpi_status status;
> + int i;
>
> if (acpi_verify_table_checksum) {
> pr_info("Early table checksum verification enabled\n");
> @@ -803,12 +804,29 @@ int __init acpi_table_init(void)
> status = acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
> if (ACPI_FAILURE(status))
> return -EINVAL;
> - acpi_table_initrd_scan();
>
> - check_multiple_madt();
> + for (i = 0; i < ACPI_MAX_TABLES; i++) {
> + struct acpi_table_desc *table_desc = &initial_tables[i];
> +
> + if (!table_desc->address || !table_desc->length)
> + break;
> +
> + pr_info("Reserving %4s table memory at [0x%llx - 0x%llx]\n",
> + table_desc->signature.ascii, table_desc->address,
> + table_desc->address + table_desc->length - 1);
> +
> + memblock_reserve(table_desc->address, table_desc->length);
> + }
> +
> return 0;
> }
>
> +void __init acpi_table_init(void)
> +{
> + acpi_table_initrd_scan();
> + check_multiple_madt();
> +}
> +
> static int __init acpi_parse_apic_instance(char *str)
> {
> if (!str)
>
>
>