Move freeing of an old enc_write_ctx/write_hash to dtls1_clear_sent_b…

…uffer

When we are clearing the sent messages queue we should ensure we free any
old enc_write_ctx/write_hash that are no longer in use. Previously this
logic was in dtls1_hm_fragment_free() - but this can end up freeing the
current enc_write_ctx/write_hash under certain error conditions.

Fixes openssl#22664

ssl/d1_lib.c

@@ -130,6 +130,23 @@ void dtls1_clear_sent_buffer(SSL *s)
 
     while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
         frag = (hm_fragment *)item->data;
+
+        if (frag->msg_header.is_ccs) {
+            /*
+            * If we're freeing the CCS then we're done with the old
+            * enc_write_ctx/write_hash and they can be freed
+            */
+            if (s->enc_write_ctx
+                    != frag->msg_header.saved_retransmit_state.enc_write_ctx)
+                EVP_CIPHER_CTX_free(frag->msg_header.saved_retransmit_state
+                                                    .enc_write_ctx);
+
+            if (s->write_hash
+                    != frag->msg_header.saved_retransmit_state.write_hash)
+                EVP_MD_CTX_free(frag->msg_header.saved_retransmit_state
+                                                .write_hash);
+        }
+
         dtls1_hm_fragment_free(frag);
         pitem_free(item);
     }

ssl/statem/statem_dtls.c

@@ -95,11 +95,7 @@ void dtls1_hm_fragment_free(hm_fragment *frag)
 {
     if (!frag)
         return;
-    if (frag->msg_header.is_ccs) {
-        EVP_CIPHER_CTX_free(frag->msg_header.
-                            saved_retransmit_state.enc_write_ctx);
-        EVP_MD_CTX_free(frag->msg_header.saved_retransmit_state.write_hash);
-    }
+
     OPENSSL_free(frag->fragment);
     OPENSSL_free(frag->reassembly);
     OPENSSL_free(frag);