[PATCH] Crypto: Fix one bug when use kernel ecdsa algorithm

[yangmengfei1394]

From: ymf <yangmengfei1394@xxxxxxxxxxxxxx>

We are trying to use kernel ecdsa algorithm to sign something.
When we call the crypto_akcipher_set_priv_key function, the
system collapses because it comes to NULL pointer.We find out
kerenl ecdsa algorithm has not offered the set_priv_key function.
So we think it might be necessary to check whether set_priv_key is
available when crypto_akcipher_set_priv_key is called.

Signed-off-by: ymf <yangmengfei1394@xxxxxxxxxxxxxx>
---
 include/crypto/akcipher.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h
index f35fd653e4e5..a68f0e23bf89 100644
--- a/include/crypto/akcipher.h
+++ b/include/crypto/akcipher.h
@@ -459,7 +459,9 @@ static inline int crypto_akcipher_set_priv_key(struct crypto_akcipher *tfm,
 					       unsigned int keylen)
 {
 	struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
-
-	return alg->set_priv_key(tfm, key, keylen);
+	if (likely(alg->set_priv_key != NULL))
+		return alg->set_priv_key(tfm, key, keylen);
+	else
+		return -EPERM;
 }
 #endif
-- 
2.34.1