Crypto/evp: Fix null pointer dereference

Check the return value of EVP_KDF_fetch to avoid a potential
null pointer dereference.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18062)

diff --git a/crypto/evp/p5_crpt2.c b/crypto/evp/p5_crpt2.c
index 7088875fe1fea9439ee5c248b14b1227d2dd42f9..4c82241f377d781dbbb55bb18d9e0e9d967f2128 100644 (file)
--- a/crypto/evp/p5_crpt2.c
+++ b/crypto/evp/p5_crpt2.c
@@ -42,6 +42,8 @@ int ossl_pkcs5_pbkdf2_hmac_ex(const char *pass, int passlen,
         salt = (unsigned char *)empty;
 
     kdf = EVP_KDF_fetch(libctx, OSSL_KDF_NAME_PBKDF2, propq);
+    if (kdf == NULL)
+         return 0;
     kctx = EVP_KDF_CTX_new(kdf);
     EVP_KDF_free(kdf);
     if (kctx == NULL)