[PATCH v2 10/25] media: lirc: validate scancode for transmit

[Sean Young]

Ensure we reject an attempt to transmit invalid scancodes.

Signed-off-by: Sean Young <s...@mess.org>
---
 drivers/media/rc/ir-lirc-codec.c |  3 +++
 drivers/media/rc/rc-core-priv.h  |  1 +
 drivers/media/rc/rc-main.c       | 53 +++++++++++++++++++++++++---------------
 3 files changed, 37 insertions(+), 20 deletions(-)

diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
index 94561d8b0c0b..863d975d40fb 100644
--- a/drivers/media/rc/ir-lirc-codec.c
+++ b/drivers/media/rc/ir-lirc-codec.c
@@ -122,6 +122,9 @@ static ssize_t ir_lirc_transmit_ir(struct file *file, const 
char __user *buf,
                    scan.timestamp)
                        return -EINVAL;
 
+               if (!rc_validate_scancode(scan.rc_proto, scan.scancode))
+                       return -EINVAL;
+
                if (dev->tx_scancode) {
                        ret = dev->tx_scancode(dev, &scan);
                        return ret < 0 ? ret : n;
diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index 21e515d34f64..a064c401fa38 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -160,6 +160,7 @@ static inline bool is_timing_event(struct ir_raw_event ev)
 #define TO_STR(is_pulse)               ((is_pulse) ? "pulse" : "space")
 
 /* functions for IR encoders */
+bool rc_validate_scancode(enum rc_proto proto, u32 scancode);
 
 static inline void init_ir_raw_event_duration(struct ir_raw_event *ev,
                                              unsigned int pulse,
diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
index 758c14b90a87..38393f13822f 100644
--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -776,6 +776,37 @@ void rc_keydown_notimeout(struct rc_dev *dev, enum 
rc_proto protocol,
 EXPORT_SYMBOL_GPL(rc_keydown_notimeout);
 
 /**
+ * rc_validate_scancode() - checks that a scancode is valid for a protocol
+ * @proto:     protocol
+ * @scancode:  scancode
+ */
+bool rc_validate_scancode(enum rc_proto proto, u32 scancode)
+{
+       switch (proto) {
+       case RC_PROTO_NECX:
+               if ((((scancode >> 16) ^ ~(scancode >> 8)) & 0xff) == 0)
+                       return false;
+               break;
+       case RC_PROTO_NEC32:
+               if ((((scancode >> 24) ^ ~(scancode >> 16)) & 0xff) == 0)
+                       return false;
+               break;
+       case RC_PROTO_RC6_MCE:
+               if ((scancode & 0xffff0000) != 0x800f0000)
+                       return false;
+               break;
+       case RC_PROTO_RC6_6A_32:
+               if ((scancode & 0xffff0000) == 0x800f0000)
+                       return false;
+               break;
+       default:
+               break;
+       }
+
+       return true;
+}
+
+/**
  * rc_validate_filter() - checks that the scancode and mask are valid and
  *                       provides sensible defaults
  * @dev:       the struct rc_dev descriptor of the device
@@ -793,26 +824,8 @@ static int rc_validate_filter(struct rc_dev *dev,
 
        mask = protocols[protocol].scancode_bits;
 
-       switch (protocol) {
-       case RC_PROTO_NECX:
-               if ((((s >> 16) ^ ~(s >> 8)) & 0xff) == 0)
-                       return -EINVAL;
-               break;
-       case RC_PROTO_NEC32:
-               if ((((s >> 24) ^ ~(s >> 16)) & 0xff) == 0)
-                       return -EINVAL;
-               break;
-       case RC_PROTO_RC6_MCE:
-               if ((s & 0xffff0000) != 0x800f0000)
-                       return -EINVAL;
-               break;
-       case RC_PROTO_RC6_6A_32:
-               if ((s & 0xffff0000) == 0x800f0000)
-                       return -EINVAL;
-               break;
-       default:
-               break;
-       }
+       if (!rc_validate_scancode(protocol, s))
+               return -EINVAL;
 
        filter->data &= mask;
        filter->mask &= mask;
-- 
2.13.6