Don't skip calling the cleanup hook in EVP_PKEY_CTX when the copy hook fails

This was only reachable from malloc failure. Way back in
https://boringssl-review.googlesource.com/c/boringssl/+/13830 we
imported a change from BoringSSL to stop calling cleanup when
EVP_PKEY_CTX_dup failed. This supposedly fixed a crash (I didn't check
if it did at the time) but instead caused different malloc failures to
leak memory.

Now that all our cleanup functions are just a call to C++ Delete, and we
use C++ scopers for all the fields, the EVP_PKEY_CTX state is in a
consistent enough state to delete all the time anyway.

While I'm here, I've fixed the cleanup functions to all be more
consistent. Some of them reset ctx->data and some of them didn't. It
doesn't matter if we do because the object will be destroyed immediately
afterwards, so I standardized on the shorter pattern.

To review this, check that a failure in the copy hook never leaves the
EVP_PKEY_CTX in a state where the cleanup hook will not safely clean
this up. Note that bssl::Delete, like C++ delete, gracefully handles
nullptr.

Change-Id: I874b953efbef179f1387c0a2b2e0320e6c3ff2e6
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/93627
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Rudolf Polzer <rpolzer@google.com>
Auto-Submit: David Benjamin <davidben@google.com>

crypto/evp/evp_ctx.cc

diff --git a/crypto/evp/evp_ctx.cc b/crypto/evp/evp_ctx.cc
index adac362..ffb9b6f 100644
--- a/crypto/evp/evp_ctx.cc
+++ b/crypto/evp/evp_ctx.cc
@@ -144,7 +144,6 @@
   ret->pkey = UpRef(impl->pkey);
   ret->peerkey = UpRef(impl->peerkey);
   if (impl->pmeth->copy(ret.get(), impl) <= 0) {
-    ret->pmeth = nullptr;  // Don't call |pmeth->cleanup|.
     OPENSSL_PUT_ERROR(EVP, ERR_LIB_EVP);
     return nullptr;
   }

crypto/evp/p_dh.cc

diff --git a/crypto/evp/p_dh.cc b/crypto/evp/p_dh.cc
index 26c4770..eaf7fad 100644
--- a/crypto/evp/p_dh.cc
+++ b/crypto/evp/p_dh.cc
@@ -189,9 +189,7 @@
 }
 
 static void pkey_dh_cleanup(EvpPkeyCtx *ctx) {
-  DH_PKEY_CTX *dctx = reinterpret_cast<DH_PKEY_CTX *>(ctx->data);
-  Delete(dctx);
-  ctx->data = nullptr;
+  Delete(reinterpret_cast<DH_PKEY_CTX *>(ctx->data));
 }
 
 static int pkey_dh_keygen(EvpPkeyCtx *ctx, EvpPkey *pkey) {

crypto/evp/p_ec.cc

diff --git a/crypto/evp/p_ec.cc b/crypto/evp/p_ec.cc
index cf58518..ac9a489 100644
--- a/crypto/evp/p_ec.cc
+++ b/crypto/evp/p_ec.cc
@@ -365,12 +365,7 @@
 }
 
 static void pkey_ec_cleanup(EvpPkeyCtx *ctx) {
-  EC_PKEY_CTX *dctx = reinterpret_cast<EC_PKEY_CTX *>(ctx->data);
-  if (!dctx) {
-    return;
-  }
-
-  Delete(dctx);
+  Delete(reinterpret_cast<EC_PKEY_CTX *>(ctx->data));
 }
 
 static int pkey_ec_sign(EvpPkeyCtx *ctx, uint8_t *sig, size_t *siglen,

crypto/evp/p_hkdf.cc

diff --git a/crypto/evp/p_hkdf.cc b/crypto/evp/p_hkdf.cc
index f1a8a35..14cb76c 100644
--- a/crypto/evp/p_hkdf.cc
+++ b/crypto/evp/p_hkdf.cc
@@ -63,9 +63,7 @@
 }
 
 static void pkey_hkdf_cleanup(EvpPkeyCtx *ctx) {
-  HKDF_PKEY_CTX *hctx = reinterpret_cast<HKDF_PKEY_CTX *>(ctx->data);
-  Delete(hctx);
-  ctx->data = nullptr;
+  Delete(reinterpret_cast<HKDF_PKEY_CTX *>(ctx->data));
 }
 
 static int pkey_hkdf_derive(EvpPkeyCtx *ctx, uint8_t *out, size_t *out_len) {