linux-kernel - Re: [PATCH v3 2/2] module: Introduce module unload taint tracking

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Message-ID: <20220421145757.zfn6zxh6rx3dp75o@ava.usersys.com>
Date:   Thu, 21 Apr 2022 15:57:57 +0100
From:   Aaron Tomlin <atomlin@...hat.com>
To:     Oleksandr Natalenko <oleksandr@...alenko.name>
Cc:     mcgrof@...nel.org, cl@...ux.com, pmladek@...e.com, mbenes@...e.cz,
        christophe.leroy@...roup.eu, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
        atomlin@...mlin.com, ghalat@...hat.com, neelx@...hat.com
Subject: Re: [PATCH v3 2/2] module: Introduce module unload taint tracking

On Thu 2022-04-21 16:28 +0200, Oleksandr Natalenko wrote:
> Hello.

Hi Oleksandr,

> Thanks for this submission. Please see one comment inline.

Thanks for your feedback!

> > @@ -150,6 +160,41 @@ int unregister_module_notifier(struct notifier_block *nb)
> >  }
> >  EXPORT_SYMBOL(unregister_module_notifier);
> >  
> > +#ifdef CONFIG_MODULE_UNLOAD_TAINT_TRACKING
> > +static int try_add_tainted_module(struct module *mod)
> > +{
> > +	struct mod_unload_taint *mod_taint;
> > +
> > +	module_assert_mutex_or_preempt();
> > +
> > +	list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules, list,
> > +				lockdep_is_held(&module_mutex)) {
> > +		size_t len = strlen(mod_taint->name);
> > +
> > +		if (len == strlen(mod->name) && !memcmp(mod_taint->name, mod->name, len) &&
> 
> Here, two strings are compared, so I'd expect to see `strncmp()` instead of `memcmp()`.

Good point. There are other examples of this throughout
kernel/module/main.c; albeit, I will use strncmp() here.


Kind regards,

-- 
Aaron Tomlin