Subject: Re: xfrm: Fix initialize repl field of struct xfrm_state

From: Steffen Klassert <[email-masked]>
Date: Mon, 21 Mar 2011 13:06:35 +0100

On Mon, Mar 21, 2011 at 05:18:18PM +0800, Wei Yongjun wrote:
> 
> >> Btw, looking a bit closer to this. I think it would look a bit cleaner
> >> if we would add the xfrm_init_replay() call to xfrm_init_state() and
> >> to move the xfrm_init_state() call in xfrm_state_construct() behind
> >> the assign of the replay settings.
> > The xfrm_init_replay() should be call after the call to
> >   xfrm_update_ae_params(x, attrs);
> > since xfrm_update_ae_params() may update the replay_esn.
> >
> > So we need move the xfrm_init_state()  call just before return x.
> 
> 
> Oh, sorry, the memcpy looks like dup code since we used
> kmemdup. It is the same attr XFRMA_REPLAY_ESN_VAL.
> 

Indeed, we don't need the memcpy here because we do a kmemdup when we
allocate repay_esn/preplay_esn. But we need to memcpy if we call
xfrm_update_ae_params() from xfrm_new_ae().

So we could just replace the kmemdup by kmalloc when we allocate
repay_esn/preplay_esn and move xfrm_init_state() at the end of the
function, as you suggested. xfrm_update_ae_params() would initialize
x->replay_esn and x->preplay_esn properly then.

> > The other issue:
> > static void xfrm_update_ae_params()
> > {
> >         ...
> >         memcpy(x->replay_esn, replay_esn,
> >                        xfrm_replay_state_esn_len(replay_esn));
> >        ...
> > }
> >
> > the memcpy() may cause memory overlap if we build a special
> > nl_data, we should free it and then do kmemdup()?
> >