[Qemu-devel] [PATCH] crypto: afalg: fix a NULL pointer dereference

["Longpeng(Mike)" <longpeng2@huawei.com>]

Test-crypto-hash calls qcrypto_hash_bytesv/digest/base64 with
errp=NULL, this will cause a NULL poniter deference if afalg_driver
doesn't support requested algos:
    ret = qcrypto_hash_afalg_driver.hash_bytesv(alg, iov, niov,
                                                result, resultlen,
                                                errp);
    if (ret == 0) {
        return ret;
    }

    error_free(*errp);  // <--- here

So we must check 'errp & *errp' before dereference.

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
---
 crypto/hash.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/crypto/hash.c b/crypto/hash.c
index ac59c63..c464c78 100644
--- a/crypto/hash.c
+++ b/crypto/hash.c
@@ -60,7 +60,9 @@ int qcrypto_hash_bytesv(QCryptoHashAlgorithm alg,
      * TODO:
      * Maybe we should treat some afalg errors as fatal
      */
-    error_free(*errp);
+    if (errp && *errp) {
+        error_free(*errp);
+    }
 #endif
 
     return qcrypto_hash_lib_driver.hash_bytesv(alg, iov, niov,
-- 
1.8.3.1