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SubjectRe: [PATCH v3 1/7] staging: r8188eu: remove unused member free_bss_buf
On Wed, Apr 20, 2022 at 02:55:34PM +0300, Dan Carpenter wrote:
> As a kernel community, I don't think we are pro-active enough about
> preventing bugs. One of my co-workers and I have started a bi weekly
> phone call to look at CVEs from the previous week and discuss how they
> could have been prevented or detected earlier. Of course, my solutions
> are always centered around static analysis because that's my deal but
> some bugs are caused by process issues, or could be detected with better
> testing.
>
> In this case there were two bugs proposed bugs.
>
> 1) The memory leak that Fabio noticed. Smatch is bad at detecting
> memory leaks. It's a hard problem, because in this case it's
> across function boundaries.
>
> Fabio caught the leak. I don't know if I would have.
>
> 2) The NULL dereference.
>
> The "&pnetwork->list" expression is not a dereference so this is also
> a cross function thing. I thought I used to have an unpublished check
> for bogus addresses like that where pnetwork is NULL.
>
> Another is idea is that when you have pnetwork++ and it's a NULL
> pointer then print an error message. Or even potentially NULL.
> There are various heuristics to use which mean that "A reasonable
> person would think this could be NULL".
>
> Or another idea would be that we could test patches. Right now we
> don't really have a way to test these. But, of course, we wish we
> did.
>
> It's not super likely that we would have committed the NULL deref
> patch. I would have caught that one if you didn't and Fabio likely
> would have as well. But I like to remove the human error whenever I
> can.
>
> regards,
> dan carpenter

I'm sorry about the NULL dereference. I wasn't sure about pnetwork
and I should've asked. I wanted to ask why pbuf should be removed
when it was being used for pnetwork but ended up not asking and
sent a faulty patch. Sorry again and thank you for explaining the
errors. I will be more careful about memory leaks and dereferencing
errors. Are there checks that I can run to detect these?

Thanks,
Jaehee

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