[PATCH v2 2/3] media: gspca/sunplus: fix zero-length control requests

[PATCH v2 2/3] media: gspca/sunplus: fix zero-length control requests

[Johan Hovold]

The direction of the pipe argument must match the request-type direction
bit or control requests may fail depending on the host-controller-driver
implementation.

Control transfers without a data stage are treated as OUT requests by
the USB stack and should be using usb_sndctrlpipe(). Failing to do so
will now trigger a warning.

Fix the single zero-length control request which was using the
read-register helper, and update the helper so that zero-length reads
fail with an error message instead.

Fixes: 6a7eba24e4f0 ("V4L/DVB (8157): gspca: all subdrivers")
Cc: stable@vger.kernel.org      # 2.6.27
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/media/usb/gspca/sunplus.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/gspca/sunplus.c b/drivers/media/usb/gspca/sunplus.c
index ace3da40006e..971dee0a56da 100644
--- a/drivers/media/usb/gspca/sunplus.c
+++ b/drivers/media/usb/gspca/sunplus.c
@@ -242,6 +242,10 @@ static void reg_r(struct gspca_dev *gspca_dev,
 		gspca_err(gspca_dev, "reg_r: buffer overflow\n");
 		return;
 	}
+	if (len == 0) {
+		gspca_err(gspca_dev, "reg_r: zero-length read\n");
+		return;
+	}
 	if (gspca_dev->usb_err < 0)
 		return;
 	ret = usb_control_msg(gspca_dev->dev,
@@ -250,7 +254,7 @@ static void reg_r(struct gspca_dev *gspca_dev,
 			USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
 			0,		/* value */
 			index,
-			len ? gspca_dev->usb_buf : NULL, len,
+			gspca_dev->usb_buf, len,
 			500);
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
@@ -727,7 +731,7 @@ static int sd_start(struct gspca_dev *gspca_dev)
 		case MegaImageVI:
 			reg_w_riv(gspca_dev, 0xf0, 0, 0);
 			spca504B_WaitCmdStatus(gspca_dev);
-			reg_r(gspca_dev, 0xf0, 4, 0);
+			reg_w_riv(gspca_dev, 0xf0, 4, 0);
 			spca504B_WaitCmdStatus(gspca_dev);
 			break;
 		default:
-- 
2.31.1

[PATCH v2 3/3] media: rtl28xxu: fix zero-length control request

[Johan Hovold]

The direction of the pipe argument must match the request-type direction
bit or control requests may fail depending on the host-controller-driver
implementation.

Control transfers without a data stage are treated as OUT requests by
the USB stack and should be using usb_sndctrlpipe(). Failing to do so
will now trigger a warning.

The driver uses a zero-length i2c-read request for type detection so
update the control-request code to use usb_sndctrlpipe() in this case.

Note that actually trying to read the i2c register in question does not
work as the register might not exist (e.g. depending on the demodulator)
as reported by Eero Lehtinen <debiangamer2@gmail.com>.

Reported-by: syzbot+faf11bbadc5a372564da@syzkaller.appspotmail.com
Reported-by: Eero Lehtinen <debiangamer2@gmail.com>
Tested-by: Eero Lehtinen <debiangamer2@gmail.com>
Fixes: d0f232e823af ("[media] rtl28xxu: add heuristic to detect chip type")
Cc: stable@vger.kernel.org      # 4.0
Cc: Antti Palosaari <crope@iki.fi>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/media/usb/dvb-usb-v2/rtl28xxu.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
index 97ed17a141bb..a6124472cb06 100644
--- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
+++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
@@ -37,7 +37,16 @@ static int rtl28xxu_ctrl_msg(struct dvb_usb_device *d, struct rtl28xxu_req *req)
 	} else {
 		/* read */
 		requesttype = (USB_TYPE_VENDOR | USB_DIR_IN);
-		pipe = usb_rcvctrlpipe(d->udev, 0);
+
+		/*
+		 * Zero-length transfers must use usb_sndctrlpipe() and
+		 * rtl28xxu_identify_state() uses a zero-length i2c read
+		 * command to determine the chip type.
+		 */
+		if (req->size)
+			pipe = usb_rcvctrlpipe(d->udev, 0);
+		else
+			pipe = usb_sndctrlpipe(d->udev, 0);
 	}
 
 	ret = usb_control_msg(d->udev, pipe, 0, requesttype, req->value,
-- 
2.31.1