From ee03cca88ec2e4cd1ffd319764cced1cab707ee2 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 16 Jul 2018 17:18:41 +0100 Subject: hw/intc/arm_gic: Check interrupt number in gic_deactivate_irq() In gic_deactivate_irq() the interrupt number comes from the guest (on a write to the GICC_DIR register), so we need to sanity check that it isn't out of range before we use it as an array index. Handle this in a similar manner to the check we do in gic_complete_irq() for the GICC_EOI register. The array overrun is not disastrous because the calling code uses (value & 0x3ff) to extract the interrupt field, so the only out-of-range values possible are 1020..1023, which allow overrunning only from irq_state[] into the following irq_target[] array which the guest can already manipulate. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Reviewed-by: Luc Michel Message-id: 20180712154152.32183-2-peter.maydell@linaro.org --- hw/intc/arm_gic.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c index ea0323f969..b0a69d6386 100644 --- a/hw/intc/arm_gic.c +++ b/hw/intc/arm_gic.c @@ -543,7 +543,21 @@ static bool gic_eoi_split(GICState *s, int cpu, MemTxAttrs attrs) static void gic_deactivate_irq(GICState *s, int cpu, int irq, MemTxAttrs attrs) { int cm = 1 << cpu; - int group = gic_has_groups(s) && GIC_TEST_GROUP(irq, cm); + int group; + + if (irq >= s->num_irq) { + /* + * This handles two cases: + * 1. If software writes the ID of a spurious interrupt [ie 1023] + * to the GICC_DIR, the GIC ignores that write. + * 2. If software writes the number of a non-existent interrupt + * this must be a subcase of "value written is not an active interrupt" + * and so this is UNPREDICTABLE. We choose to ignore it. + */ + return; + } + + group = gic_has_groups(s) && GIC_TEST_GROUP(irq, cm); if (!gic_eoi_split(s, cpu, attrs)) { /* This is UNPREDICTABLE; we choose to ignore it */ -- cgit v1.2.3