Clean up EVP_EncryptFinal_ex()

This switches to the variable names used in other functions, adds a
reminder to add a missing length check and uses memset for the padding.

ok jsing

diff --git a/lib/libcrypto/evp/evp_enc.c b/lib/libcrypto/evp/evp_enc.c
index 16a993e..b001505 100644 (file)
--- a/lib/libcrypto/evp/evp_enc.c
+++ b/lib/libcrypto/evp/evp_enc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: evp_enc.c,v 1.64 2023/12/20 10:35:25 tb Exp $ */
+/* $OpenBSD: evp_enc.c,v 1.65 2023/12/20 10:42:43 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -382,38 +382,35 @@ EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
 int
 EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
 {
-       int n;
-       unsigned int i, b, bl;
+       const int block_size = ctx->cipher->block_size;
+       int buf_offset = ctx->buf_len;
+       int pad;
 
        *outl = 0;
 
        if ((ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) != 0)
                return evp_cipher(ctx, out, outl, NULL, 0);
 
-       b = ctx->cipher->block_size;
-       if (b > sizeof ctx->buf) {
+       /* XXX - check that block_size > buf_offset. */
+       if (block_size > sizeof(ctx->buf)) {
                EVPerror(EVP_R_BAD_BLOCK_LENGTH);
                return 0;
        }
-       if (b == 1) {
-               *outl = 0;
+       if (block_size == 1)
                return 1;
-       }
-       bl = ctx->buf_len;
-       if (ctx->flags & EVP_CIPH_NO_PADDING) {
-               if (bl) {
+
+       if ((ctx->flags & EVP_CIPH_NO_PADDING) != 0) {
+               if (buf_offset != 0) {
                        EVPerror(EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH);
                        return 0;
                }
-               *outl = 0;
                return 1;
        }
 
-       n = b - bl;
-       for (i = bl; i < b; i++)
-               ctx->buf[i] = n;
+       pad = block_size - buf_offset;
+       memset(&ctx->buf[buf_offset], pad, pad);
 
-       return evp_cipher(ctx, out, outl, ctx->buf, b);
+       return evp_cipher(ctx, out, outl, ctx->buf, block_size);
 }
 
 int