From dad5ab0db8deac535d03e3fe3d8f2892173fa6a4 Mon Sep 17 00:00:00 2001 From: Seunghun Han Date: Tue, 18 Jul 2017 20:03:51 +0900 Subject: [PATCH] x86/acpi: Prevent out of bound access caused by broken ACPI tables The bus_irq argument of mp_override_legacy_irq() is used as the index into the isa_irq_to_gsi[] array. The bus_irq argument originates from ACPI_MADT_TYPE_IO_APIC and ACPI_MADT_TYPE_INTERRUPT items in the ACPI tables, but is nowhere sanity checked. That allows broken or malicious ACPI tables to overwrite memory, which might cause malfunction, panic or arbitrary code execution. Add a sanity check and emit a warning when that triggers. [ tglx: Added warning and rewrote changelog ] Signed-off-by: Seunghun Han Signed-off-by: Thomas Gleixner Cc: security@kernel.org Cc: "Rafael J. Wysocki" Cc: stable@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/acpi/boot.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 6bb680671088..7491e73d9253 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -346,6 +346,14 @@ static void __init mp_override_legacy_irq(u8 bus_irq, u8 polarity, u8 trigger, int pin; struct mpc_intsrc mp_irq; + /* + * Check bus_irq boundary. + */ + if (bus_irq >= NR_IRQS_LEGACY) { + pr_warn("Invalid bus_irq %u for legacy override\n", bus_irq); + return; + } + /* * Convert 'gsi' to 'ioapic.pin'. */