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

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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



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