[PATCH] efi_loader: EFI TCG2 free efi memory on protocol failure

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Thu, Mar 25, 2021 at 11:10:26AM +0100, Heinrich Schuchardt wrote:
> On 24.03.21 15:23, Ilias Apalodimas wrote:
> > Current code doesn't free the efi allocated memory in case the protocol
> > failed to install
> >
> > Fixes: c8d0fd582576 ("efi_loader: Introduce eventlog support for TCG2_PROTOCOL")
> > Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> > ---
> >  lib/efi_loader/efi_tcg2.c | 21 +++++++++++++++++----
> >  1 file changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> > index 797d6eb134f6..02de63808f9a 100644
> > --- a/lib/efi_loader/efi_tcg2.c
> > +++ b/lib/efi_loader/efi_tcg2.c
> > @@ -988,6 +988,7 @@ static efi_status_t create_final_event(void)
> >
> >  	return EFI_SUCCESS;
> >  out:
> > +	efi_free_pool(event_log.final_buffer);
> >  	return ret;
> >  }
> >
> > @@ -1041,8 +1042,12 @@ static efi_status_t efi_init_event_log(void)
> >  	event_log.last_event_size = event_log.pos;
> >
> >  	ret = create_final_event();
> 
> Shouldn't create_final_event() should free event_log.final_buffer if
> efi_install_configuration_table() fails?
> 

I am not sure I undetstand you here. 
create_final_event() frees event_log.final_buffer if installing the config 
table fails.

> > +	if (ret != EFI_SUCCESS)
> > +		goto out;
> >
> > +	return EFI_SUCCESS;
> >  out:
> > +	efi_free_pool(event_log.buffer);
> 
> We must set event_log.buffer to NULL to avoid double free?

Yea sure

> 
> >  	return ret;
> >  }
> >
> > @@ -1055,23 +1060,31 @@ out:
> >   */
> >  efi_status_t efi_tcg2_register(void)
> >  {
> > -	efi_status_t ret;
> > +	efi_status_t ret = EFI_SUCCESS;
> >  	struct udevice *dev;
> >
> >  	ret = platform_get_tpm2_device(&dev);
> >  	if (ret != EFI_SUCCESS) {
> >  		log_warning("Unable to find TPMv2 device\n");
> > -		return EFI_SUCCESS;
> > +		ret = EFI_SUCCESS;
> > +		goto out;
> >  	}
> >
> >  	ret = efi_init_event_log();
> >  	if (ret != EFI_SUCCESS)
> > -		return ret;
> > +		goto fail;
> >
> >  	ret = efi_add_protocol(efi_root, &efi_guid_tcg2_protocol,
> >  			       (void *)&efi_tcg2_protocol);
> > -	if (ret != EFI_SUCCESS)
> > +	if (ret != EFI_SUCCESS) {
> >  		log_err("Cannot install EFI_TCG2_PROTOCOL\n");
> > +		goto fail;
> > +	}
> >
> > +out:
> > +	return ret;
> > +fail:
> 
> In create_final_event() you have installed a configuration table
> EFI_TCG2_FINAL_EVENTS_TABLE_GUID. You should not free the memory of the
> configuration table without uninstalling the table.
> 
> Should we create separate uninit function which takes care of the logic?

I guess I could gather all the frees/uninstalles in one function and call that
explicitly

> 
> Best regards
> 
> Heinrich
> 
> > +	efi_free_pool(event_log.final_buffer);
> > +	efi_free_pool(event_log.buffer);
> >  	return ret;
> >  }
> >
>