lkml.org 
[lkml]   [2012]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 66/76] ACPI: Fix use-after-free in acpi_map_lsapic
    Date
    From: Petr Vandrovec <petr@vmware.com>

    When processor is being hot-added to the system, acpi_map_lsapic invokes
    ACPI _MAT method to find APIC ID and flags, verifies that returned structure
    is indeed ACPI's local APIC structure, and that flags contain MADT_ENABLED
    bit. Then saves APIC ID, frees structure - and accesses structure when
    computing arguments for acpi_register_lapic call. Which sometime leads
    to acpi_register_lapic call being made with second argument zero, failing
    to bring processor online with error 'Unable to map lapic to logical cpu
    number'.

    As lapic->lapic_flags & ACPI_MADT_ENABLED was already confirmed to be non-zero
    few lines above, we can just pass unconditional ACPI_MADT_ENABLED to the
    acpi_register_lapic.

    Signed-off-by: Petr Vandrovec <petr@vmware.com>
    Signed-off-by: Alok N Kataria <akataria@vmware.com>
    Reviewed-by: Toshi Kani <toshi.kani@hp.com>
    Signed-off-by: Len Brown <len.brown@intel.com>
    ---
    arch/x86/kernel/acpi/boot.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
    index ce664f3..bbcc2c3 100644
    --- a/arch/x86/kernel/acpi/boot.c
    +++ b/arch/x86/kernel/acpi/boot.c
    @@ -642,6 +642,7 @@ static int __cpuinit _acpi_map_lsapic(acpi_handle handle, int *pcpu)
    kfree(buffer.pointer);
    buffer.length = ACPI_ALLOCATE_BUFFER;
    buffer.pointer = NULL;
    + lapic = NULL;

    if (!alloc_cpumask_var(&tmp_map, GFP_KERNEL))
    goto out;
    @@ -650,7 +651,7 @@ static int __cpuinit _acpi_map_lsapic(acpi_handle handle, int *pcpu)
    goto free_tmp_map;

    cpumask_copy(tmp_map, cpu_present_mask);
    - acpi_register_lapic(physid, lapic->lapic_flags & ACPI_MADT_ENABLED);
    + acpi_register_lapic(physid, ACPI_MADT_ENABLED);

    /*
    * If mp_register_lapic successfully generates a new logical cpu
    --
    1.7.10.rc2.19.gfae9d


    \
     
     \ /
      Last update: 2012-03-30 14:21    [W:4.180 / U:0.060 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site