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 <kkamagui@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: security@kernel.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit dad5ab0db8deac535d03e3fe3d8f2892173fa6a4)

Orabug: 26540612
CVE: CVE-2017-11473

Signed-off-by: Tim Tianyang Chen <tianyang.chen@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index b15fbeaf92fbf038c92da3b08b2fcba912bbf315..1e32f9133a49af0e8f51fb474de5bd61d1e0773e 100644 (file)
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -336,6 +336,14 @@ 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'.
         */