[PATCH 6.6 014/396] serial: max310x: fix NULL pointer dereference in I2C instantiation

Greg Kroah-Hartman
2024-04-01T16:35:19Z

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

[ Upstream commit 0d27056c24efd3d63a03f3edfbcfc4827086b110 ]

When trying to instantiate a max14830 device from userspace:

echo max14830 0x60 > /sys/bus/i2c/devices/i2c-2/new_device

we get the following error:

Unable to handle kernel NULL pointer dereference at virtual address...
...
Call trace:
max310x_i2c_probe+0x48/0x170 [max310x]
i2c_device_probe+0x150/0x2a0
...

Add check for validity of devtype to prevent the error, and abort probe
with a meaningful error message.

Fixes: 2e1f2d9a9bdb ("serial: max310x: implement I2C support")
Cc: stable@vger.kernel.org
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20240118152213.2644269-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/max310x.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 4814aa310dcc5..e339abff926d3 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1635,13 +1635,16 @@ static unsigned short max310x_i2c_slave_addr(unsigned short addr,

static int max310x_i2c_probe(struct i2c_client *client)
{
- const struct max310x_devtype *devtype =
- device_get_match_data(&client->dev);
+ const struct max310x_devtype *devtype;
struct i2c_client *port_client;
struct regmap *regmaps[4];
unsigned int i;
u8 port_addr;

+ devtype = device_get_match_data(&client->dev);
+ if (!devtype)
+ return dev_err_probe(&client->dev, -ENODEV, "Failed to match device\n");
+
if (client->addr < devtype->slave_addr.min ||
client->addr > devtype->slave_addr.max)
return dev_err_probe(&client->dev, -EINVAL,
--
2.43.0