Messages in this thread Patch in this message | | | Date | Wed, 15 Feb 2012 16:06:43 -0800 | From | Petr Vandrovec <> | Subject | [PATCH 3.3.0-rc3] Fix use-after-free in acpi_map_lsapic |
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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.
Thanks, Petr
Signed-off-by: Petr Vandrovec <petr@vmware.com> Signed-off-by: Alok Kataria <akataria@vmware.com>
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index ce664f3..a4a0901 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -650,7 +650,7 @@ 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
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