`EVP_PKEY_CTX_dup` segmentation fault fix

CLA: trivial
The the provider, context duplication method for signature, key
exchange, asymmetric cipher, and key encapsulation is optional. But if
they are missing, we will get a segmentation fault in `EVP_PKEY_CTX_dup`
because they are called without null pointer checking.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20581)

diff --git a/crypto/evp/pmeth_lib.c b/crypto/evp/pmeth_lib.c
index 249c895a15977b7798832173dfc2f4a246203711..caf10b2d5c968d2e3ab003696a50af5f9ecae4bc 100644 (file)
--- a/crypto/evp/pmeth_lib.c
+++ b/crypto/evp/pmeth_lib.c
@@ -503,8 +503,11 @@ EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *pctx)
         if (pctx->op.kex.algctx != NULL) {
             if (!ossl_assert(pctx->op.kex.exchange != NULL))
                 goto err;
-            rctx->op.kex.algctx
-                = pctx->op.kex.exchange->dupctx(pctx->op.kex.algctx);
+
+            if (pctx->op.kex.exchange->dupctx != NULL)
+                rctx->op.kex.algctx
+                    = pctx->op.kex.exchange->dupctx(pctx->op.kex.algctx);
+
             if (rctx->op.kex.algctx == NULL) {
                 EVP_KEYEXCH_free(rctx->op.kex.exchange);
                 rctx->op.kex.exchange = NULL;
@@ -521,8 +524,11 @@ EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *pctx)
         if (pctx->op.sig.algctx != NULL) {
             if (!ossl_assert(pctx->op.sig.signature != NULL))
                 goto err;
-            rctx->op.sig.algctx
-                = pctx->op.sig.signature->dupctx(pctx->op.sig.algctx);
+
+            if (pctx->op.sig.signature->dupctx != NULL)
+                rctx->op.sig.algctx
+                    = pctx->op.sig.signature->dupctx(pctx->op.sig.algctx);
+
             if (rctx->op.sig.algctx == NULL) {
                 EVP_SIGNATURE_free(rctx->op.sig.signature);
                 rctx->op.sig.signature = NULL;
@@ -539,8 +545,11 @@ EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *pctx)
         if (pctx->op.ciph.algctx != NULL) {
             if (!ossl_assert(pctx->op.ciph.cipher != NULL))
                 goto err;
-            rctx->op.ciph.algctx
-                = pctx->op.ciph.cipher->dupctx(pctx->op.ciph.algctx);
+
+            if (pctx->op.ciph.cipher->dupctx != NULL)
+                rctx->op.ciph.algctx
+                    = pctx->op.ciph.cipher->dupctx(pctx->op.ciph.algctx);
+
             if (rctx->op.ciph.algctx == NULL) {
                 EVP_ASYM_CIPHER_free(rctx->op.ciph.cipher);
                 rctx->op.ciph.cipher = NULL;
@@ -557,8 +566,11 @@ EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *pctx)
         if (pctx->op.encap.algctx != NULL) {
             if (!ossl_assert(pctx->op.encap.kem != NULL))
                 goto err;
-            rctx->op.encap.algctx
-                = pctx->op.encap.kem->dupctx(pctx->op.encap.algctx);
+
+            if (pctx->op.encap.kem->dupctx != NULL)
+                rctx->op.encap.algctx
+                    = pctx->op.encap.kem->dupctx(pctx->op.encap.algctx);
+
             if (rctx->op.encap.algctx == NULL) {
                 EVP_KEM_free(rctx->op.encap.kem);
                 rctx->op.encap.kem = NULL;