From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Vandrovec Subject: [PATCH 3.3.0-rc3] Fix use-after-free in acpi_map_lsapic Date: Wed, 15 Feb 2012 16:06:43 -0800 Message-ID: <20120216000643.GA7508@petr-dev3.eng.vmware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: lenb@kernel.org Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, akataria@vmware.com, dcovelli@vmware.com List-Id: linux-acpi@vger.kernel.org From: Petr Vandrovec 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 Signed-off-by: Alok Kataria 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