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tpm2: Always use a temporary buffer for decryption

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Always use a temporary buffer large enough to meet the requirements of the
EVP_DecryptUpdate() call.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
This commit is contained in:
Stefan Berger 2020-05-23 19:25:58 -04:00 committed by Stefan Berger
parent 2233af9ca1
commit 78de69d2d4
1 changed files with 16 additions and 16 deletions
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32
src/tpm2/crypto/openssl/CryptSym.c
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@ -632,8 +632,7 @@ CryptSymmetricDecrypt(
EVP_CIPHER_CTX *ctx = NULL;
int outlen1 = 0;
int outlen2 = 0;
BYTE *pOut = dOut;
BYTE *buffer = NULL;
BYTE *buffer;
UINT32 buffersize = 0;
BYTE keyToUse[MAX_SYM_KEY_BYTES];
UINT16 keyToUseLen = (UINT16)sizeof(keyToUse);
@ -681,18 +680,15 @@ CryptSymmetricDecrypt(
if (evpfn == NULL)
return TPM_RC_FAILURE;
if (dIn == dOut) {
// in-place encryption; we use a temp buffer
buffersize = TPM2_ROUNDUP(dSize, blockSize);
buffer = malloc(buffersize);
if (buffer == NULL)
ERROR_RETURN(TPM_RC_FAILURE);
pOut = buffer;
}
/* a buffer with a 'safety margin' for EVP_DecryptUpdate */
buffersize = TPM2_ROUNDUP(dSize + blockSize, blockSize);
buffer = malloc(buffersize);
if (buffer == NULL)
ERROR_RETURN(TPM_RC_FAILURE);
#if ALG_TDES && ALG_CTR
if (algorithm == TPM_ALG_TDES && mode == ALG_CTR_VALUE) {
TDES_CTR(keyToUse, keyToUseLen * 8, dSize, dIn, iv, pOut, blockSize);
TDES_CTR(keyToUse, keyToUseLen * 8, dSize, dIn, iv, buffer, blockSize);
outlen1 = dSize;
ERROR_RETURN(TPM_RC_SUCCESS);
}
@ -702,17 +698,21 @@ CryptSymmetricDecrypt(
if (!ctx ||
EVP_DecryptInit_ex(ctx, evpfn(), NULL, keyToUse, iv) != 1 ||
EVP_CIPHER_CTX_set_padding(ctx, 0) != 1 ||
EVP_DecryptUpdate(ctx, pOut, &outlen1, dIn, dSize) != 1)
EVP_DecryptUpdate(ctx, buffer, &outlen1, dIn, dSize) != 1)
ERROR_RETURN(TPM_RC_FAILURE);
pAssert(outlen1 <= dSize || dSize >= outlen1 + blockSize);
pAssert((int)buffersize >= outlen1);
if (EVP_DecryptFinal(ctx, pOut + outlen1, &outlen2) != 1)
if (EVP_DecryptFinal(ctx, &buffer[outlen1], &outlen2) != 1)
ERROR_RETURN(TPM_RC_FAILURE);
pAssert((int)buffersize >= outlen1 + outlen2);
Exit:
if (retVal == TPM_RC_SUCCESS && pOut != dOut)
memcpy(dOut, pOut, outlen1 + outlen2);
if (retVal == TPM_RC_SUCCESS) {
pAssert(dSize >= outlen1 + outlen2);
memcpy(dOut, buffer, outlen1 + outlen2);
}
clear_and_free(buffer, buffersize);
EVP_CIPHER_CTX_free(ctx);