[PATCH 5.4 178/320] media: m920x: dont use stack on USB reads

Greg Kroah-Hartman
2022-01-24T19:40:46Z

From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

[ Upstream commit a2ab06d7c4d6bfd0b545a768247a70463e977e27 ]

Using stack-allocated pointers for USB message data don't work.
This driver is almost OK with that, except for the I2C read
logic.

Fix it by using a temporary read buffer, just like on all other
calls to m920x_read().

Link: https://lore.kernel.org/all/ccc99e48-de4f-045e-0fe4-61e3118e3f74@mida.se/
Reported-by: rkardell@mida.se
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/usb/dvb-usb/m920x.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/dvb-usb/m920x.c b/drivers/media/usb/dvb-usb/m920x.c
index d866a1990a7d2..7282f60226558 100644
--- a/drivers/media/usb/dvb-usb/m920x.c
+++ b/drivers/media/usb/dvb-usb/m920x.c
@@ -274,6 +274,13 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu
/* Should check for ack here, if we knew how. */
}
if (msg[i].flags & I2C_M_RD) {
+ char *read = kmalloc(1, GFP_KERNEL);
+ if (!read) {
+ ret = -ENOMEM;
+ kfree(read);
+ goto unlock;
+ }
+
for (j = 0; j < msg[i].len; j++) {
/* Last byte of transaction?
* Send STOP, otherwise send ACK. */
@@ -281,9 +288,12 @@ 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,
- &msg[i].buf[j], 1)) != 0)
+ read, 1)) != 0)
goto unlock;
+ msg[i].buf[j] = read[0];
}
+
+ kfree(read);
} else {
for (j = 0; j < msg[i].len; j++) {
/* Last byte of transaction? Then send STOP. */
--
2.34.1