[PATCH] KEYS: asymmetric: fix error return code in software_key_query()

[PATCH] KEYS: asymmetric: fix error return code in software_key_query()

[Wei Yongjun]

Fix to return negative error code -ENOMEM from kmalloc() error handling
case instead of 0, as done elsewhere in this function.

Fixes: f1774cb8956a ("X.509: parse public key parameters from x509 for akcipher")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
---
 crypto/asymmetric_keys/public_key.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index d7f43d4ea925..c15bde024b4c 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -119,6 +119,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);
 
+	ret = -ENOMEM;
 	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 		      GFP_KERNEL);
 	if (!key)

[PATCH] keys: asymmetric: fix error return code in software_key_query()

[David Howells]

From: Wei Yongjun <weiyongjun1@huawei.com>

Fix to return negative error code -ENOMEM from kmalloc() error handling
case instead of 0, as done elsewhere in this function.

Fixes: f1774cb8956a ("X.509: parse public key parameters from x509 for akcipher")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 crypto/asymmetric_keys/public_key.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index d7f43d4ea925..e5fae4e838c0 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -119,6 +119,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);
 
+	ret = -ENOMEM;
 	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 		      GFP_KERNEL);
 	if (!key)

Re: [PATCH] keys: asymmetric: fix error return code in software_key_query()

[Jarkko Sakkinen]

On Wed, Jul 15, 2020 at 11:28:38PM +0100, David Howells wrote:
> From: Wei Yongjun <weiyongjun1@huawei.com>
> 
> Fix to return negative error code -ENOMEM from kmalloc() error handling
> case instead of 0, as done elsewhere in this function.
> 
> Fixes: f1774cb8956a ("X.509: parse public key parameters from x509 for akcipher")
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> Signed-off-by: David Howells <dhowells@redhat.com>

Why f1774cb8956a lacked any possible testing? It extends ABI anyway.

I think it is a kind of change that would require more screening before
getting applied.

> ---
> 
>  crypto/asymmetric_keys/public_key.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> index d7f43d4ea925..e5fae4e838c0 100644
> --- a/crypto/asymmetric_keys/public_key.c
> +++ b/crypto/asymmetric_keys/public_key.c
> @@ -119,6 +119,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
>  	if (IS_ERR(tfm))
>  		return PTR_ERR(tfm);
>  
> +	ret = -ENOMEM;

This is extremely confusing to read way to handle 'ret'.

Would be way more cleaner to be just simple and stupid:

	if (!key) {
		ret = -ENOMEM;
		goto error_free_tfm;
	}

>  	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
>  		      GFP_KERNEL);
>  	if (!key)

/Jarkko

Re: [PATCH] keys: asymmetric: fix error return code in software_key_query()

[Jarkko Sakkinen]

On Thu, Jul 23, 2020 at 04:32:38AM +0300, Jarkko Sakkinen wrote:
> On Wed, Jul 15, 2020 at 11:28:38PM +0100, David Howells wrote:
> > From: Wei Yongjun <weiyongjun1@huawei.com>
> > 
> > Fix to return negative error code -ENOMEM from kmalloc() error handling
> > case instead of 0, as done elsewhere in this function.
> > 
> > Fixes: f1774cb8956a ("X.509: parse public key parameters from x509 for akcipher")
> > Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> > Signed-off-by: David Howells <dhowells@redhat.com>
> 
> Why f1774cb8956a lacked any possible testing? It extends ABI anyway.
> 
> I think it is a kind of change that would require more screening before
> getting applied.
> 
> > ---
> > 
> >  crypto/asymmetric_keys/public_key.c |    1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> > index d7f43d4ea925..e5fae4e838c0 100644
> > --- a/crypto/asymmetric_keys/public_key.c
> > +++ b/crypto/asymmetric_keys/public_key.c
> > @@ -119,6 +119,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
> >  	if (IS_ERR(tfm))
> >  		return PTR_ERR(tfm);
> >  
> > +	ret = -ENOMEM;
> 
> This is extremely confusing to read way to handle 'ret'.
> 
> Would be way more cleaner to be just simple and stupid:
> 
> 	if (!key) {
> 		ret = -ENOMEM;
> 		goto error_free_tfm;
> 	}

To rationalize why the 2nd way is better: the diff would tell the
whole story. Now this commit requires to check *both* the diff and
the source file to get the full understanding what is going on.

/Jarkko

Re: [PATCH] keys: asymmetric: fix error return code in software_key_query()

[David Howells]

Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote:

> >  	if (IS_ERR(tfm))
> >  		return PTR_ERR(tfm);
> >  
> > +	ret = -ENOMEM;
> 
> This is extremely confusing to read way to handle 'ret'.
> 
> Would be way more cleaner to be just simple and stupid:
> 
> 	if (!key) {
> 		ret = -ENOMEM;
> 		goto error_free_tfm;
> 	}

I agree, but we have some people who will (or who used to) moan at you for
doing in four lines what you could've done in three.  I don't know if this is
still the standard.

David

Re: [PATCH] keys: asymmetric: fix error return code in software_key_query()

[David Howells]

Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote:

> Why f1774cb8956a lacked any possible testing? It extends ABI anyway.
> 
> I think it is a kind of change that would require more screening before
> getting applied.

Yeah.  It went in via a round-about route.  I left off development of it when
the tpm stuff I wrote broke because the tpm2 stuff went in upstream.  I then
handed the patches off to Denis who did the tpm support, but I never got my
stuff finished enough to work out how to do the testsuite (since it would
involve using a tpm).  However, since I did the PKCS#8 testing module as well,
I guess I don't need that to at least test the API.  I'll look at using that
to add some tests.  Any suggestions as to how to do testing via the tpm?

David

Re: [PATCH] keys: asymmetric: fix error return code in software_key_query()

[Jarkko Sakkinen]

On Thu, Jul 23, 2020 at 08:42:25AM +0100, David Howells wrote:
> Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote:
> 
> > Why f1774cb8956a lacked any possible testing? It extends ABI anyway.
> > 
> > I think it is a kind of change that would require more screening before
> > getting applied.
> 
> Yeah.  It went in via a round-about route.  I left off development of it when
> the tpm stuff I wrote broke because the tpm2 stuff went in upstream.  I then
> handed the patches off to Denis who did the tpm support, but I never got my
> stuff finished enough to work out how to do the testsuite (since it would
> involve using a tpm).  However, since I did the PKCS#8 testing module as well,
> I guess I don't need that to at least test the API.  I'll look at using that
> to add some tests.  Any suggestions as to how to do testing via the tpm?
> 
> David

The unfortunate thing is that I was not involved with asym_tpm.c review
process in any possible way, which means that at the moment I lack both:

1. Knowledge of crypto/asymmetric_keys.
2. How asym_tpm.c is implemented.

I only became aware of asym_tpm.c's existence last Sep [*].

I'll put to my backlog to try TPM asymmetric keys (earliest when I'm back
from vacation 08/10).

[*] https://lore.kernel.org/linux-integrity/20190926171601.30404-1-jarkko.sakkinen@linux.intel.com/

/Jarkko