[PATCH v2] Input: iforce - validate input packet lengths

[Pengpeng Hou]

iforce_process_packet() reads fixed fields from joystick, wheel and status
packets without first checking their lengths. In particular, the shared
hats-and-buttons helper unconditionally reads data[6]. The status tail is
a sequence of 16-bit effect addresses, but an incomplete final address is
also consumed. A successful zero-length USB URB additionally reads the
packet ID before the common parser is called.

Reject the zero-length USB transfer, require the seven-byte joystick and
wheel prefixes and the two-byte status prefix, and consume only complete
status-tail addresses.

Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
Changes since v1: https://lore.kernel.org/all/20260706092016.78176-1-pengpeng@xxxxxxxxxxx/
- cover the data[6] access in the shared hats-and-buttons helper
- cover zero-length USB completions and incomplete status-tail u16 values
- rebase onto v7.2-rc4

 drivers/input/joystick/iforce/iforce-packets.c | 11 ++++++++++-
 drivers/input/joystick/iforce/iforce-usb.c     |  3 +++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/input/joystick/iforce/iforce-packets.c b/drivers/input/joystick/iforce/iforce-packets.c
index effa76bfd8f9..e8a34d68a51f 100644
--- a/drivers/input/joystick/iforce/iforce-packets.c
+++ b/drivers/input/joystick/iforce/iforce-packets.c
@@ -155,6 +155,9 @@ void iforce_process_packet(struct iforce *iforce,
 	switch (packet_id) {
 
 	case 0x01:	/* joystick position data */
+		if (len < 7)
+			break;
+
 		input_report_abs(dev, ABS_X,
 				 (__s16) get_unaligned_le16(data));
 		input_report_abs(dev, ABS_Y,
@@ -170,6 +173,9 @@ void iforce_process_packet(struct iforce *iforce,
 		break;
 
 	case 0x03:	/* wheel position data */
+		if (len < 7)
+			break;
+
 		input_report_abs(dev, ABS_WHEEL,
 				 (__s16) get_unaligned_le16(data));
 		input_report_abs(dev, ABS_GAS,   255 - data[2]);
@@ -181,6 +187,9 @@ void iforce_process_packet(struct iforce *iforce,
 		break;
 
 	case 0x02:	/* status report */
+		if (len < 2)
+			break;
+
 		input_report_key(dev, BTN_DEAD, data[0] & 0x02);
 		input_sync(dev);
 
@@ -200,7 +209,7 @@ void iforce_process_packet(struct iforce *iforce,
 			}
 		}
 
-		for (j = 3; j < len; j += 2)
+		for (j = 3; j + sizeof(u16) <= len; j += 2)
 			mark_core_as_ready(iforce, get_unaligned_le16(data + j));
 
 		break;
diff --git a/drivers/input/joystick/iforce/iforce-usb.c b/drivers/input/joystick/iforce/iforce-usb.c
index 0482eaaecf39..f04370e4191e 100644
--- a/drivers/input/joystick/iforce/iforce-usb.c
+++ b/drivers/input/joystick/iforce/iforce-usb.c
@@ -158,6 +158,9 @@ static void iforce_usb_irq(struct urb *urb)
 		goto exit;
 	}
 
+	if (!urb->actual_length)
+		goto exit;
+
 	iforce_process_packet(iforce, iforce_usb->data_in[0],
 			      iforce_usb->data_in + 1, urb->actual_length - 1);