linux-kernel - [PATCH 3.16 079/328] media: dvb-usb-v2/gl861: ensure USB message buffers DMA'able

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Message-ID: <lsq.1544392233.73992011@decadent.org.uk>
Date:   Sun, 09 Dec 2018 21:50:33 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Mauro Carvalho Chehab" <mchehab+samsung@...nel.org>,
        "Akihiro Tsukada" <tskd08@...il.com>
Subject: [PATCH 3.16 079/328] media: dvb-usb-v2/gl861: ensure USB message
 buffers DMA'able

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Akihiro Tsukada <tskd08@...il.com>

commit 86f65c218123c4e36fd855fbbc38147ffaf29974 upstream.

i2c message buf might be on stack.

Signed-off-by: Akihiro Tsukada <tskd08@...il.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/usb/dvb-usb-v2/gl861.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

--- a/drivers/media/usb/dvb-usb-v2/gl861.c
+++ b/drivers/media/usb/dvb-usb-v2/gl861.c
@@ -20,6 +20,8 @@ static int gl861_i2c_msg(struct dvb_usb_
 	u16 value = addr << (8 + 1);
 	int wo = (rbuf == NULL || rlen == 0); /* write-only */
 	u8 req, type;
+	u8 *buf;
+	int ret;
 
 	if (wo) {
 		req = GL861_REQ_I2C_WRITE;
@@ -42,11 +44,23 @@ static int gl861_i2c_msg(struct dvb_usb_
 				KBUILD_MODNAME, wlen);
 		return -EINVAL;
 	}
-
+	buf = NULL;
+	if (rlen > 0) {
+		buf = kmalloc(rlen, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+	}
 	msleep(1); /* avoid I2C errors */
 
-	return usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), req, type,
-			       value, index, rbuf, rlen, 2000);
+	ret = usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), req, type,
+			      value, index, buf, rlen, 2000);
+	if (rlen > 0) {
+		if (ret > 0)
+			memcpy(rbuf, buf, rlen);
+		kfree(buf);
+	}
+
+	return ret;
 }
 
 /* I2C */