Re: [PATCH] leds: fix a potential NULL pointer dereference

From: Jacek Anaszewski
Date: Sun Mar 31 2019 - 07:06:28 EST


Hi Geert,

Thank you for the notification.

On 3/31/19 11:06 AM, Geert Uytterhoeven wrote:
Hi Jacek,

On Sun, Mar 10, 2019 at 9:40 PM Jacek Anaszewski
<jacek.anaszewski@xxxxxxxxx> wrote:
On 3/9/19 7:04 AM, Kangjie Lu wrote:
In case of_match_device cannot find a match, the fixes returns
-EINVAL to avoid NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>
---
drivers/leds/leds-pca9532.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
index 7fea18b0c15d..4b0335591728 100644
--- a/drivers/leds/leds-pca9532.c
+++ b/drivers/leds/leds-pca9532.c
@@ -513,6 +513,7 @@ static int pca9532_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
int devid;
+ const struct of_device_id *of_id;
struct pca9532_data *data = i2c_get_clientdata(client);
struct pca9532_platform_data *pca9532_pdata =
dev_get_platdata(&client->dev);
@@ -528,8 +529,11 @@ static int pca9532_probe(struct i2c_client *client,
dev_err(&client->dev, "no platform data\n");
return -EINVAL;
}
- devid = (int)(uintptr_t)of_match_device(
- of_pca9532_leds_match, &client->dev)->data;
+ of_id = of_match_device(of_pca9532_leds_match,
+ &client->dev);
+ if (unlikely(!of_id))

Use of unlikey() is frowned upon.

What do you mean? Can you give some reference?

Moreover, this cannot happen, as pca9532_of_populate_pdata() already
contains a similar check.

Right, I assumed this fixes a real problem and didn't spent too much
time investigating the whole context.. Lesson for the future.

Kangjie: please stop submitting patches for missing checks, without
investigating if the failures can actually happen. Thanks!

+ return -EINVAL;
+ devid = (int)of_id->data;
} else {
devid = id->driver_data;
}


Applied to the for-5.2 branch of linux-leds.git.

And also as a fix for v5.1...

Yes, but it had been in linux-next for almost two weeks before that.

--
Best regards,
Jacek Anaszewski