hw/display/tc6393xb: limit irq handler index to TC6393XB_GPIOS

The ctz32() routine could return a value greater than
TC6393XB_GPIOS=16, because the device has 24 GPIO level
bits but we only implement 16 outgoing lines. This could
lead to an OOB array access. Mask 'level' to avoid it.

Reported-by: Moguofang <moguofang@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 20171212041539.25700-1-ppandit@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/display/tc6393xb.c b/hw/display/tc6393xb.c
index 74d10af3d4187c7c746db664d293be1a94fe9aea..0ae63605f01db41fb262e51dc926bc73f26c9b2c 100644 (file)
--- a/hw/display/tc6393xb.c
+++ b/hw/display/tc6393xb.c
@@ -172,6 +172,7 @@ static void tc6393xb_gpio_handler_update(TC6393xbState *s)
     int bit;
 
     level = s->gpio_level & s->gpio_dir;
+    level &= MAKE_64BIT_MASK(0, TC6393XB_GPIOS);
 
     for (diff = s->prev_level ^ level; diff; diff ^= 1 << bit) {
         bit = ctz32(diff);