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>

1 files changed, 11 insertions, 6 deletions

diff --git a/drivers/media/IR/ir-sysfs.c b/drivers/media/IR/ir-sysfs.c
index 96dafc425c8e..46d42467f9b4 100644
--- a/drivers/media/IR/ir-sysfs.c
+++ b/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);