media: dvb-usb: m920x: Fix a potential memory leak in m920x_i2c_xfer()

[ Upstream commit ea9ef6c ]

'read' is freed when it is known to be NULL, but not when a read error
occurs.

Revert the logic to avoid a small leak, should a m920x_read() call fail.

Fixes: a2ab06d ("media: m920x: don't use stack on USB reads")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/media/usb/dvb-usb/m920x.c

@@ -277,7 +277,6 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu
 			char *read = kmalloc(1, GFP_KERNEL);
 			if (!read) {
 				ret = -ENOMEM;
-				kfree(read);
 				goto unlock;
 			}
 
@@ -288,8 +287,10 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu
 
 				if ((ret = m920x_read(d->udev, M9206_I2C, 0x0,
 						      0x20 | stop,
-						      read, 1)) != 0)
+						      read, 1)) != 0) {
+					kfree(read);
 					goto unlock;
+				}
 				msg[i].buf[j] = read[0];
 			}