Re: [PATCH] ima: avoid appraise error for hash calc interrupt

[Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>]

On 11/12/2019 9:14 AM, Mimi Zohar wrote:

> On Mon, 2019-11-11 at 14:29 -0800, Lakshmi Ramasubramanian wrote:
> > On 11/11/19 11:23 AM, Patrick Callaghan wrote:
> >
> > > -		if (rbuf_len == 0)
> > > +		if (rbuf_len == 0) {	/* unexpected EOF */
> > > +			rc = -EINVAL;
> > >    			break;
> > > +		}
> > >    		offset += rbuf_len;
> >
> > Should there be an additional check to validate that (offset + rbuf_len)
> > is less than i_size before calling cypto_shash_update (since rbuf_len is
> > one of the parameters for this call)?
>
> The "while" statement enforces that.
>
> Mimi

Yes - but that check happens after the call to crypto_shash_update().

Perhaps integrity_kernel_read() will never return (rbuf_len) that will
 => violate the check in the "while" statement.
 => number of bytes read that is greater than the memory allocated for 
rbuf even in error conditions.

Just making sure.

thanks,
 -lakshmi

> >                  if ((rbuf_len == 0) || (offset + rbuf_len >= i_size)) {
> >                           rc = -EINVAL;
> >                           break;
> >                  }
> >                  offset += rbuf_len;
> >
> > >    	       rc = crypto_shash_update(shash, rbuf, rbuf_len);