[PATCH v5 03/15] media: redrat3: Ensure we don't read beyond the end of the packet

The length and offset is provided by the usb device, so it should be
validated.

Fixes: 2154be651b90 ("[media] redrat3: new rc-core IR transceiver device driver")
Signed-off-by: Sean Young <[email protected]>
Cc: [email protected]
---
 drivers/media/rc/redrat3.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/media/rc/redrat3.c b/drivers/media/rc/redrat3.c
index 2b639fe59923..f86efcb74e6e 100644
--- a/drivers/media/rc/redrat3.c
+++ b/drivers/media/rc/redrat3.c
@@ -358,8 +358,24 @@ static void redrat3_process_ir_data(struct redrat3_dev *rr3)
 
 	/* process each rr3 encoded byte into an int */
 	sig_size = be16_to_cpu(rr3->irdata.sig_size);
+
+	/*
+	 * Note we are not checking if we are reading beyond the end of the
+	 * packet which was sent, and reading stale data. If the device
+	 * sends a packet which is short then we get garbage IR, but no
+	 * out of bounds read.
+	 */
+	if (sig_size > RR3_MAX_SIG_SIZE) {
+		dev_err(dev, "length %u is incorrect\n", sig_size);
+		return;
+	}
+
 	for (i = 0; i < sig_size; i++) {
 		offset = rr3->irdata.sigdata[i];
+		if (offset >= RR3_DRIVER_MAXLENS) {
+			dev_err(dev, "offset %u is incorrect\n", offset);
+			return;
+		}
 		val = get_unaligned_be16(&rr3->irdata.lens[offset]);
 
 		/* we should always get pulse/space/pulse/space samples */
-- 
2.55.0