From 05901b497de1bdf3d67cb1093d3582b2dc1b0416 Mon Sep 17 00:00:00 2001
From: miod <miod@openbsd.org>
Date: Sun, 13 Jul 2014 11:14:02 +0000
Subject: [PATCH] EVP_DigestInit_ex() may be used to recycle an existing
 EVP_MD_CTX without having to reinitialize all of it, especially if it is used
 with the same MD algorithm.

However, when the MD algorithm changes, it needs to perform more cleanups.
Make that code more closer to what EVP_MD_CTX_cleanup() does by:
- only freeing md_data if EVP_MD_CTX_FLAG_REUSE is not set
- performing an explicit_bzero of md_data before freeing it
- making sure we call EVP_PKEY_CTX_free on the pctx if the allocation for the
  new md_data fails.

ok tedu@
---
 lib/libcrypto/evp/digest.c         | 12 +++++++++---
 lib/libssl/src/crypto/evp/digest.c | 12 +++++++++---
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/lib/libcrypto/evp/digest.c b/lib/libcrypto/evp/digest.c
index d582d7954e5..a1be18ee225 100644
--- a/lib/libcrypto/evp/digest.c
+++ b/lib/libcrypto/evp/digest.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: digest.c,v 1.22 2014/07/12 16:03:37 miod Exp $ */
+/* $OpenBSD: digest.c,v 1.23 2014/07/13 11:14:02 miod Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -192,13 +192,19 @@ EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl)
 	}
 #endif
 	if (ctx->digest != type) {
-		if (ctx->digest && ctx->digest->ctx_size)
+		if (ctx->digest && ctx->digest->ctx_size && ctx->md_data &&
+		    !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE)) {
+			explicit_bzero(ctx->md_data, ctx->digest->ctx_size);
 			free(ctx->md_data);
+			ctx->md_data = NULL;
+		}
 		ctx->digest = type;
 		if (!(ctx->flags & EVP_MD_CTX_FLAG_NO_INIT) && type->ctx_size) {
 			ctx->update = type->update;
 			ctx->md_data = malloc(type->ctx_size);
 			if (ctx->md_data == NULL) {
+				EVP_PKEY_CTX_free(ctx->pctx);
+				ctx->pctx = NULL;
 				EVPerr(EVP_F_EVP_DIGESTINIT_EX,
 				    ERR_R_MALLOC_FAILURE);
 				return 0;
@@ -355,7 +361,7 @@ EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx)
 		ctx->digest->cleanup(ctx);
 	if (ctx->digest && ctx->digest->ctx_size && ctx->md_data &&
 	    !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE)) {
-		OPENSSL_cleanse(ctx->md_data, ctx->digest->ctx_size);
+		explicit_bzero(ctx->md_data, ctx->digest->ctx_size);
 		free(ctx->md_data);
 	}
 	EVP_PKEY_CTX_free(ctx->pctx);
diff --git a/lib/libssl/src/crypto/evp/digest.c b/lib/libssl/src/crypto/evp/digest.c
index d582d7954e5..a1be18ee225 100644
--- a/lib/libssl/src/crypto/evp/digest.c
+++ b/lib/libssl/src/crypto/evp/digest.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: digest.c,v 1.22 2014/07/12 16:03:37 miod Exp $ */
+/* $OpenBSD: digest.c,v 1.23 2014/07/13 11:14:02 miod Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -192,13 +192,19 @@ EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl)
 	}
 #endif
 	if (ctx->digest != type) {
-		if (ctx->digest && ctx->digest->ctx_size)
+		if (ctx->digest && ctx->digest->ctx_size && ctx->md_data &&
+		    !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE)) {
+			explicit_bzero(ctx->md_data, ctx->digest->ctx_size);
 			free(ctx->md_data);
+			ctx->md_data = NULL;
+		}
 		ctx->digest = type;
 		if (!(ctx->flags & EVP_MD_CTX_FLAG_NO_INIT) && type->ctx_size) {
 			ctx->update = type->update;
 			ctx->md_data = malloc(type->ctx_size);
 			if (ctx->md_data == NULL) {
+				EVP_PKEY_CTX_free(ctx->pctx);
+				ctx->pctx = NULL;
 				EVPerr(EVP_F_EVP_DIGESTINIT_EX,
 				    ERR_R_MALLOC_FAILURE);
 				return 0;
@@ -355,7 +361,7 @@ EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx)
 		ctx->digest->cleanup(ctx);
 	if (ctx->digest && ctx->digest->ctx_size && ctx->md_data &&
 	    !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE)) {
-		OPENSSL_cleanse(ctx->md_data, ctx->digest->ctx_size);
+		explicit_bzero(ctx->md_data, ctx->digest->ctx_size);
 		free(ctx->md_data);
 	}
 	EVP_PKEY_CTX_free(ctx->pctx);
-- 
2.20.1