From 81b37fec23ed86ff12224584b8d9c5ba60d06b72 Mon Sep 17 00:00:00 2001
From: tb <tb@openbsd.org>
Date: Wed, 7 Sep 2022 21:17:32 +0000
Subject: [PATCH] Add output length validation for EVP

From Joshua Sing
---
 regress/lib/libcrypto/rc4/rc4_test.c | 30 ++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/regress/lib/libcrypto/rc4/rc4_test.c b/regress/lib/libcrypto/rc4/rc4_test.c
index a4094854a0f..49da63540ff 100644
--- a/regress/lib/libcrypto/rc4/rc4_test.c
+++ b/regress/lib/libcrypto/rc4/rc4_test.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rc4_test.c,v 1.3 2022/09/05 21:36:46 tb Exp $ */
+/*	$OpenBSD: rc4_test.c,v 1.4 2022/09/07 21:17:32 tb Exp $ */
 /*
  * Copyright (c) 2022 Joshua Sing <joshua@hypera.dev>
  *
@@ -323,7 +323,7 @@ rc4_test(void)
 	EVP_CIPHER_CTX *ctx = NULL;
 	const EVP_CIPHER *cipher;
 	uint8_t out[512];
-	int in_len, out_len;
+	int in_len, out_len, total_len;
 	size_t i;
 	int j;
 	int failed = 1;
@@ -369,6 +369,7 @@ rc4_test(void)
 		}
 
 		/* EVP encryption */
+		total_len = 0;
 		memset(out, 0, sizeof(out));
 		if (!EVP_EncryptInit(ctx, cipher, rt->key, NULL)) {
 			fprintf(stderr, "FAIL: EVP_EncryptInit failed\n");
@@ -380,7 +381,7 @@ rc4_test(void)
 			if (in_len > rt->len - j)
 				in_len = rt->len - j;
 
-			if (!EVP_EncryptUpdate(ctx, out + j, &out_len,
+			if (!EVP_EncryptUpdate(ctx, out + total_len, &out_len,
 			    rt->in + j, in_len)) {
 				fprintf(stderr,
 				    "FAIL: EVP_EncryptUpdate failed\n");
@@ -388,24 +389,33 @@ rc4_test(void)
 			}
 
 			j += in_len;
+			total_len += out_len;
 		}
 
-		if (!EVP_EncryptFinal_ex(ctx, out, &out_len)) {
+		if (!EVP_EncryptFinal_ex(ctx, out + total_len, &out_len)) {
 			fprintf(stderr, "FAIL: EVP_EncryptFinal_ex failed\n");
 			goto failed;
 		}
+		total_len += out_len;
 
 		if (!EVP_CIPHER_CTX_reset(ctx)) {
 			fprintf(stderr, "FAIL: EVP_CIPHER_CTX_reset failed\n");
 			goto failed;
 		}
 
+		if (total_len != rt->len) {
+			fprintf(stderr,
+			    "FAIL: EVP encryption length mismatch\n");
+			goto failed;
+		}
+
 		if (memcmp(rt->out, out, rt->len) != 0) {
 			fprintf(stderr, "FAIL: EVP encryption mismatch\n");
 			goto failed;
 		}
 
 		/* EVP decryption */
+		total_len = 0;
 		memset(out, 0, sizeof(out));
 		if (!EVP_DecryptInit(ctx, cipher, rt->key, NULL)) {
 			fprintf(stderr, "FAIL: EVP_DecryptInit failed\n");
@@ -417,7 +427,7 @@ rc4_test(void)
 			if (in_len > rt->len - j)
 				in_len = rt->len - j;
 
-			if (!EVP_DecryptUpdate(ctx, out + j, &out_len,
+			if (!EVP_DecryptUpdate(ctx, out + total_len, &out_len,
 			    rt->in + j, in_len)) {
 				fprintf(stderr,
 				    "FAIL: EVP_DecryptUpdate failed\n");
@@ -425,18 +435,26 @@ rc4_test(void)
 			}
 
 			j += in_len;
+			total_len += out_len;
 		}
 
-		if (!EVP_DecryptFinal_ex(ctx, out, &out_len)) {
+		if (!EVP_DecryptFinal_ex(ctx, out + total_len, &out_len)) {
 			fprintf(stderr, "FAIL: EVP_DecryptFinal_ex failed\n");
 			goto failed;
 		}
+		total_len += out_len;
 
 		if (!EVP_CIPHER_CTX_reset(ctx)) {
 			fprintf(stderr, "FAIL: EVP_CIPHER_CTX_reset failed\n");
 			goto failed;
 		}
 
+		if (total_len != rt->len) {
+			fprintf(stderr,
+			    "FAIL: EVP decryption length mismatch\n");
+			goto failed;
+		}
+
 		if (memcmp(rt->out, out, rt->len) != 0) {
 			fprintf(stderr, "FAIL: EVP decryption mismatch\n");
 			goto failed;
-- 
2.20.1