[Ksummit-discuss] uninitialized variables bugs

Krzysztof Kozlowski
2022-05-22T09:07:52Z

On 06/05/2022 11:13, Dan Carpenter wrote:
> There is also stuff like this which is harmless:
>
> uint val;
>
> ret = read(&val);
> *p = val; // <-- uninitialized variable if read() fails
> return ret;
>
> Btw, here is how to run Smatch on your code:
> https://staticthinking.wordpress.com/2022/04/25/how-to-run-smatch-on-your-code/

In the topic of suppressing false positives we also have several
"fixes", sometimes pointed out incorrectly by Coverity, for missing
check for of_device_get_match_data().

Compare:
https://elixir.bootlin.com/linux/v5.18-rc7/source/drivers/clk/clk-aspeed.c#L415
https://elixir.bootlin.com/linux/v5.18-rc7/source/drivers/clk/clk-oxnas.c#L216

Although in theory the of_device_get_match_data() can return NULL, in
practice it is not possible because driver matches via OF thus there
will be always of_device_id->driver data.

Coverity screams about it, people fix it by adding checks for NULL,
which is pointless. Half of drivers add the !NULL check, half do not...

Best regards,
Krzysztof