Re: [POC 2/7] livepatch: Allow to handle lifetime of shadow variables using the livepatch state

[Petr Mladek]

On Thu 2024-07-25 13:31:40, Miroslav Benes wrote:
> > diff --git a/kernel/livepatch/state.c b/kernel/livepatch/state.c
> > index 6693d808106b..4ec65afe3a43 100644
> > --- a/kernel/livepatch/state.c
> > +++ b/kernel/livepatch/state.c
> > @@ -198,11 +198,17 @@ void klp_release_states(struct klp_patch *patch)
> >             if (is_state_in_other_patches(patch, state))
> >                     continue;
> >  
> > -           if (!state->callbacks.release)
> > -                   continue;
> > -
> > -           if (state->callbacks.setup_succeeded)
> > +           if (state->callbacks.release && 
> > state->callbacks.setup_succeeded)
> >                     state->callbacks.release(patch, state);
> > +
> > +           if (state->is_shadow)
> > +                   klp_shadow_free_all(state->id, 
> > state->callbacks.shadow_dtor);
> 
> The following
> 
> > +           /*
> > +            * The @release callback is supposed to restore the original
> > +            * state before the @setup callback was called.
> > +            */
> > +           state->callbacks.setup_succeeded = 0;
> 
> should go to the previous patch perhaps?

Great catch!

I am going to refactor the code in the next version so that it would
look like:

void klp_states_post_unpatch(struct klp_patch *patch)
{
        struct klp_state *state;

        klp_for_each_state(patch, state) {
                if (is_state_in_other_patches(patch, state))
                        continue;

                if (!state->callbacks.pre_patch_succeeded)
                        continue;

                if (state->callbacks.post_unpatch)
                        state->callbacks.post_unpatch(patch, state);

+               if (state->is_shadow)
+                       klp_shadow_free_all(state->id, 
state->callbacks.shadow_dtor);
+
                state->callbacks.pre_patch_succeeded = 0;
        }
}


Best Regards,
Petr