V4L/DVB: ir-core: Fix null dereferences in the protocols sysfs interface

For some cards, ir_dev->props and ir_dev->raw are both NULL. These cards are
using built-in IR decoding instead of raw, and can't easily be made to switch
protocols.

So upon reading /sys/class/rc/rc?/protocols on such a card, return 'builtin' as
the supported and enabled protocol. Return -EINVAL on any attempts to change
the protocol. And most important of all, don't crash.

Signed-off-by: Brian Rogers <brian@xyzw.org>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/IR/ir-sysfs.c

@@ -67,13 +67,14 @@ static ssize_t show_protocols(struct device *d,
 	char *tmp = buf;
 	int i;
 
-	if (ir_dev->props->driver_type == RC_DRIVER_SCANCODE) {
+	if (ir_dev->props && ir_dev->props->driver_type == RC_DRIVER_SCANCODE) {
 		enabled = ir_dev->rc_tab.ir_type;
 		allowed = ir_dev->props->allowed_protos;
-	} else {
+	} else if (ir_dev->raw) {
 		enabled = ir_dev->raw->enabled_protocols;
 		allowed = ir_raw_get_allowed_protocols();
-	}
+	} else
+		return sprintf(tmp, "[builtin]\n");
 
 	IR_dprintk(1, "allowed - 0x%llx, enabled - 0x%llx\n",
 		   (long long)allowed,
@@ -121,10 +122,14 @@ static ssize_t store_protocols(struct device *d,
 	int rc, i, count = 0;
 	unsigned long flags;
 
-	if (ir_dev->props->driver_type == RC_DRIVER_SCANCODE)
+	if (ir_dev->props && ir_dev->props->driver_type == RC_DRIVER_SCANCODE)
 		type = ir_dev->rc_tab.ir_type;
-	else
+	else if (ir_dev->raw)
 		type = ir_dev->raw->enabled_protocols;
+	else {
+		IR_dprintk(1, "Protocol switching not supported\n");
+		return -EINVAL;
+	}
 
 	while ((tmp = strsep((char **) &data, " \n")) != NULL) {
 		if (!*tmp)
@@ -185,7 +190,7 @@ static ssize_t store_protocols(struct device *d,
 		}
 	}
 
-	if (ir_dev->props->driver_type == RC_DRIVER_SCANCODE) {
+	if (ir_dev->props && ir_dev->props->driver_type == RC_DRIVER_SCANCODE) {
 		spin_lock_irqsave(&ir_dev->rc_tab.lock, flags);
 		ir_dev->rc_tab.ir_type = type;
 		spin_unlock_irqrestore(&ir_dev->rc_tab.lock, flags);