Do not pass input length <= 0 to the cipher handlers

Input length < 0 is an error and input length == 0 can result in
strange effects in some ciphers, except in CCM mode, which is extra
special.

Based on OpenSSL 420cb707 by Matt Caswell and Richard Levitte

found by & ok jsing

1 files changed, 17 insertions, 11 deletions

diff --git a/src/lib/libcrypto/evp/evp_enc.c b/src/lib/libcrypto/evp/evp_enc.c
index 896b9e1a16..d925ed77d7 100644
--- a/src/lib/libcrypto/evp/evp_enc.c
+++ b/src/lib/libcrypto/evp/evp_enc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: evp_enc.c,v 1.44 2021/02/18 19:12:29 tb Exp $ */
+/* $OpenBSD: evp_enc.c,v 1.45 2022/07/26 19:50:06 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -300,6 +300,14 @@ EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
 {
         int i, j, bl;
 
+        *outl = 0;
+
+        if (inl < 0)
+                return 0;
+
+        if (inl == 0 && EVP_CIPHER_mode(ctx->cipher) != EVP_CIPH_CCM_MODE)
+                return 1;
+
         if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
                 i = M_do_cipher(ctx, out, in, inl);
                 if (i < 0)
@@ -309,11 +317,6 @@ EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                 return 1;
         }
 
-        if (inl <= 0) {
-                *outl = 0;
-                return inl == 0;
-        }
-
         if (ctx->buf_len == 0 && (inl&(ctx->block_mask)) == 0) {
                 if (M_do_cipher(ctx, out, in, inl)) {
                         *outl = inl;
@@ -438,6 +441,14 @@ EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
         int fix_len;
         unsigned int b;
 
+        *outl = 0;
+
+        if (inl < 0)
+                return 0;
+
+        if (inl == 0 && EVP_CIPHER_mode(ctx->cipher) != EVP_CIPH_CCM_MODE)
+                return 1;
+
         if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
                 fix_len = M_do_cipher(ctx, out, in, inl);
                 if (fix_len < 0) {
@@ -448,11 +459,6 @@ EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                 return 1;
         }
 
-        if (inl <= 0) {
-                *outl = 0;
-                return inl == 0;
-        }
-
         if (ctx->flags & EVP_CIPH_NO_PADDING)
                 return EVP_EncryptUpdate(ctx, out, outl, in, inl);