[PATCH] HID: pxrc: fix slab-out-of-bounds read/write in pxrc_raw_event()

[Jinmo Yang <jinmo44.yang@gmail.com>]

pxrc_raw_event() accesses data[7] without verifying that the buffer is
large enough. A device that sends a report shorter than 8 bytes causes
an out-of-bounds read (priv->dial = data[7]) and an out-of-bounds write
(data[7] = priv->dial) on the report buffer, corrupting adjacent slab
memory.

This can be triggered from userspace via /dev/uhid by creating a virtual
device with VID 0x1781 / PID 0x0898 and sending a short UHID_INPUT2
report.

Add a size check at the top of pxrc_raw_event() to bail out when the
report buffer is shorter than 8 bytes.

Fixes: a2dccedac664 ("HID: pxrc: new driver for PhoenixRC Flight Controller Adapter")
Cc: stable@vger.kernel.org
Signed-off-by: Jinmo Yang <jinmo44.yang@gmail.com>
---
 drivers/hid/hid-pxrc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hid/hid-pxrc.c b/drivers/hid/hid-pxrc.c
index 07e20ff6018e..f2524547c7a1 100644
--- a/drivers/hid/hid-pxrc.c
+++ b/drivers/hid/hid-pxrc.c
@@ -53,6 +53,9 @@ static int pxrc_raw_event(struct hid_device *hdev, struct hid_report *report,
 		 u8 *data, int size)
 {
 	struct pxrc_priv *priv = hid_get_drvdata(hdev);
+
+	if (size < 8)
+		return 0;

 	if (priv->alternate)
 		priv->slider = data[7];
--
2.47.0