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    SubjectRe: [PATCH 1/1] ACPI: fix acpi table use after free
    Date
    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?

    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)


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