[PATCH 1/3] crypto: Fix the pointer voodoo in unaligned ahash

[Herbert Xu]

On Tue, Jan 14, 2014 at 01:35:50PM -0600, Tom Lendacky wrote:
> 
> On Tuesday, January 14, 2014 06:33:47 PM Marek Vasut wrote:
> > Add documentation for the pointer voodoo that is happening in crypto/ahash.c
> > in ahash_op_unaligned(). This code is quite confusing, so add a beefy chunk
> > of documentation.
> > 
> > Moreover, make sure the mangled request is completely restored after finishing
> > this unaligned operation. This means restoring all of .result, .priv, .base.data
> > and .base.complete .
> > 
> > Also, remove the crypto_completion_t complete = ... line present in the
> > ahash_op_unaligned_done() function. This type actually declares a function
> > pointer, which is very confusing.
> > 
> > Finally, yet very important nonetheless, make sure the req->priv is free()'d
> > only after the original request is restored in ahash_op_unaligned_done().
> > The req->priv data must not be free()'d before that in ahash_op_unaligned_finish(),
> > since we would be accessing previously free()'d data in ahash_op_unaligned_done()
> > and cause corruption.
> > 
> > Signed-off-by: Marek Vasut <marex at denx.de>
> > Cc: David S. Miller <davem at davemloft.net>
> > Cc: Fabio Estevam <fabio.estevam at freescale.com>
> > Cc: Herbert Xu <herbert at gondor.apana.org.au>
> > Cc: Shawn Guo <shawn.guo at linaro.org>
> > Cc: Tom Lendacky <thomas.lendacky at amd.com>
> > ---
> >  crypto/ahash.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++----------
> >  1 file changed, 54 insertions(+), 11 deletions(-)
> > 
> > diff --git a/crypto/ahash.c b/crypto/ahash.c
> > index a92dc38..5ca8ede 100644
> > --- a/crypto/ahash.c
> > +++ b/crypto/ahash.c
> > @@ -29,6 +29,7 @@
> >  struct ahash_request_priv {
> >  	crypto_completion_t complete;
> >  	void *data;
> > +	void *priv;
> >  	u8 *result;
> >  	void *ubuf[] CRYPTO_MINALIGN_ATTR;
> >  };
> > @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct ahash_request *req, int err)
> >  	if (!err)
> >  		memcpy(priv->result, req->result,
> >  		       crypto_ahash_digestsize(crypto_ahash_reqtfm(req)));
> > -
> > -	kzfree(priv);
> 
> You can't move/remove this kzfree since a synchronous operation will not take
> the ahash_op_unaligned_done path.  A synchronous operation will never return
> -EINPROGRESS and the effect will be to never free the priv structure.

Marek, did you have a chance to address this?

Thanks,
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt