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Commit ac909ec3 authored by Petr Vandrovec's avatar Petr Vandrovec Committed by Len Brown
Browse files

ACPI: Fix use-after-free in acpi_map_lsapic 



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: default avatarPetr Vandrovec <petr@vmware.com>
Signed-off-by: default avatarAlok N Kataria <akataria@vmware.com>
Reviewed-by: default avatarToshi Kani <toshi.kani@hp.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent c80f5b31

arch/x86/kernel/acpi/boot.c

+2 −1
Original line number Diff line number Diff line
@@ -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