[1/2] crypto: s5p - deal gracefully with bogus input sizes

Message ID 20190819142226.1703-2-ard.biesheuvel@linaro.org
State New
Headers show
Series
  • drivers/crypto - s5p fixes
Related show

Commit Message

Ard Biesheuvel Aug. 19, 2019, 2:22 p.m.
The s5p skcipher driver returns -EINVAL for zero length inputs, which
deviates from the behavior of the generic ECB template, and causes fuzz
tests to fail. In cases where the input is not a multiple of the AES
block size (and the chaining mode is not CTR), it prints an error to
the kernel log, which is a thing we usually try to avoid in response
to situations that can be triggered by unprivileged users.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 drivers/crypto/s5p-sss.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

-- 
2.17.1

Comments

Kamil Konieczny Aug. 20, 2019, 9:51 a.m. | #1
On 19.08.2019 16:22, Ard Biesheuvel wrote:
> The s5p skcipher driver returns -EINVAL for zero length inputs, which

> deviates from the behavior of the generic ECB template, and causes fuzz

> tests to fail. In cases where the input is not a multiple of the AES

> block size (and the chaining mode is not CTR), it prints an error to

> the kernel log, which is a thing we usually try to avoid in response

> to situations that can be triggered by unprivileged users.

> 

> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> ---

>  drivers/crypto/s5p-sss.c | 5 ++++-

>  1 file changed, 4 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c

> index 9ef25230c199..ef90c58edb1f 100644

> --- a/drivers/crypto/s5p-sss.c

> +++ b/drivers/crypto/s5p-sss.c

> @@ -2056,9 +2056,12 @@ static int s5p_aes_crypt(struct ablkcipher_request *req, unsigned long mode)

>  	struct s5p_aes_ctx *ctx = crypto_ablkcipher_ctx(tfm);

>  	struct s5p_aes_dev *dev = ctx->dev;

>  

> +	if (!req->nbytes)

> +		return 0;

> +

>  	if (!IS_ALIGNED(req->nbytes, AES_BLOCK_SIZE) &&

>  			((mode & FLAGS_AES_MODE_MASK) != FLAGS_AES_CTR)) {

> -		dev_err(dev->dev, "request size is not exact amount of AES blocks\n");

> +		dev_dbg(dev->dev, "request size is not exact amount of AES blocks\n");

>  		return -EINVAL;

>  	}


Acked-by: Kamil Konieczny <k.konieczny@partner.samsung.com>


-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland

Patch

diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
index 9ef25230c199..ef90c58edb1f 100644
--- a/drivers/crypto/s5p-sss.c
+++ b/drivers/crypto/s5p-sss.c
@@ -2056,9 +2056,12 @@  static int s5p_aes_crypt(struct ablkcipher_request *req, unsigned long mode)
 	struct s5p_aes_ctx *ctx = crypto_ablkcipher_ctx(tfm);
 	struct s5p_aes_dev *dev = ctx->dev;
 
+	if (!req->nbytes)
+		return 0;
+
 	if (!IS_ALIGNED(req->nbytes, AES_BLOCK_SIZE) &&
 			((mode & FLAGS_AES_MODE_MASK) != FLAGS_AES_CTR)) {
-		dev_err(dev->dev, "request size is not exact amount of AES blocks\n");
+		dev_dbg(dev->dev, "request size is not exact amount of AES blocks\n");
 		return -EINVAL;
 	}