[PATCH] crypto: testmgr - don't DMA map IV from stack in test_skcipher()

[PATCH] crypto: testmgr - don't DMA map IV from stack in test_skcipher()

[Horia Geantă]

Fix the "DMA-API: device driver maps memory from stack" warning
generated when crypto accelerators map the IV.

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
---
 crypto/testmgr.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 500a5277cc22..64245aeef634 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -1081,12 +1081,16 @@ static int __test_skcipher(struct crypto_skcipher *tfm, int enc,
 	const char *e, *d;
 	struct tcrypt_result result;
 	void *data;
-	char iv[MAX_IVLEN];
+	char *iv;
 	char *xbuf[XBUFSIZE];
 	char *xoutbuf[XBUFSIZE];
 	int ret = -ENOMEM;
 	unsigned int ivsize = crypto_skcipher_ivsize(tfm);
 
+	iv = kmalloc(MAX_IVLEN, GFP_KERNEL);
+	if (!iv)
+		return ret;
+
 	if (testmgr_alloc_buf(xbuf))
 		goto out_nobuf;
 
@@ -1328,6 +1332,7 @@ static int __test_skcipher(struct crypto_skcipher *tfm, int enc,
 out_nooutbuf:
 	testmgr_free_buf(xbuf);
 out_nobuf:
+	kfree(iv);
 	return ret;
 }
 
-- 
2.4.4

Re: [PATCH] crypto: testmgr - don't DMA map IV from stack in test_skcipher()

[Herbert Xu]

On Fri, Jan 13, 2017 at 08:59:16AM +0200, Horia Geantă wrote:
> Fix the "DMA-API: device driver maps memory from stack" warning
> generated when crypto accelerators map the IV.
> 
> Signed-off-by: Horia Geantă <horia.geanta@nxp.com>

Hmm, the IV comes in as a pointer.  So you should not assume that
it can be DMAed at all.

Perhaps we should change the API so that it gets passed in as an
SG list.

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

Re: [PATCH] crypto: testmgr - don't DMA map IV from stack in test_skcipher()

[Horia Geantă]

On 1/13/2017 10:46 AM, Herbert Xu wrote:
> On Fri, Jan 13, 2017 at 08:59:16AM +0200, Horia Geantă wrote:
>> Fix the "DMA-API: device driver maps memory from stack" warning
>> generated when crypto accelerators map the IV.
>>
>> Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
> 
> Hmm, the IV comes in as a pointer.  So you should not assume that
> it can be DMAed at all.
> 
That's correct, thanks for pointing it out.

> Perhaps we should change the API so that it gets passed in as an
> SG list.
> 
Since changing the API and converting the users looks pretty lengthy,
would it be acceptable to fix tcrypt for now?
Indeed, I've missed updating test_skcipher_speed, I can add this in v2.

Thanks,
Horia

Re: [PATCH] crypto: testmgr - don't DMA map IV from stack in test_skcipher()

[Herbert Xu]

On Wed, Mar 08, 2017 at 01:04:14PM +0000, Horia Geantă wrote:
>
> Since changing the API and converting the users looks pretty lengthy,
> would it be acceptable to fix tcrypt for now?
> Indeed, I've missed updating test_skcipher_speed, I can add this in v2.

Might as well leave it there because at least it reminds us to
fix the problem.  With the API as it is any new kernel user could
potentially provide us with an IV off the stack.

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