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Use safe math to computer sizes.

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The sizes are rounded via the expression: (cmpl + 7) / 8 which overflows if
cmpl is near to the type's maximum.  Instead we use the safe_math function to
computer this without any possibility of error.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17884)
This commit is contained in:
Pauli 2022-03-15 14:28:07 +11:00
parent 4157a32867
commit 330ff7e67d
1 changed files with 5 additions and 2 deletions
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7
crypto/evp/evp_enc.c
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@ -24,9 +24,12 @@
#include "internal/cryptlib.h"
#include "internal/provider.h"
#include "internal/core.h"
#include "internal/safe_math.h"
#include "crypto/evp.h"
#include "evp_local.h"
OSSL_SAFE_MATH_SIGNED(int, int)
int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx)
{
if (ctx == NULL)
@ -517,7 +520,7 @@ static int evp_EncryptDecryptUpdate(EVP_CIPHER_CTX *ctx,
int i, j, bl, cmpl = inl;
if (EVP_CIPHER_CTX_test_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS))
cmpl = (cmpl + 7) / 8;
cmpl = safe_div_round_up_int(cmpl, 8, NULL);
bl = ctx->cipher->block_size;
@ -803,7 +806,7 @@ int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
b = ctx->cipher->block_size;
if (EVP_CIPHER_CTX_test_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS))
cmpl = (cmpl + 7) / 8;
cmpl = safe_div_round_up_int(cmpl, 8, NULL);
if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
if (b == 1 && ossl_is_partially_overlapping(out, in, cmpl)) {