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F-1899 : fix potential heap buffer over-read #220

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64fe29e
fix f-1899 potential heap buffer over-read
miyazakh Apr 8, 2026
84cfd0c
addressed Copilot review comments
miyazakh Apr 8, 2026
7d03ee9
Addressed code review
miyazakh Apr 17, 2026
95c91af
Addressed review comments
miyazakh Apr 17, 2026
8a01c6d
Addressed review comments
miyazakh Apr 17, 2026
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274 changes: 155 additions & 119 deletions src/sign-verify/clu_sign.c
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Original file line number Diff line number Diff line change
Expand Up @@ -205,11 +205,23 @@ int wolfCLU_sign_data_rsa(byte* data, char* out, word32 dataSz, char* privKey,
}
}
if (ret == 0) {
XFSEEK(privKeyFile, 0, SEEK_END);
if (XFSEEK(privKeyFile, 0, SEEK_END) != 0) {
wolfCLU_LogError("Failed to seek to end of file.");
ret = WOLFCLU_FATAL_ERROR;
}
}
if (ret == 0) {
privFileSz = (int)XFTELL(privKeyFile);
keyBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (keyBuf == NULL) {
ret = MEMORY_E;
if (privFileSz > 0 && privFileSz <= (RSA_MAX_SIZE / 8 * 16)) {
keyBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT,
DYNAMIC_TYPE_TMP_BUFFER);
if (keyBuf == NULL) {
ret = MEMORY_E;
}
}
else {
wolfCLU_LogError("Incorrect private key file size: %d", privFileSz);
ret = WOLFCLU_FATAL_ERROR;
}
}
if (ret == 0) {
Expand Down Expand Up @@ -268,7 +280,9 @@ int wolfCLU_sign_data_rsa(byte* data, char* out, word32 dataSz, char* privKey,
ret = BAD_FUNC_ARG;
}
else {
XFWRITE(outBuf, 1, outBufSz, s);
if ((int)XFWRITE(outBuf, 1, outBufSz, s) <= 0) {
ret = OUTPUT_FILE_ERROR;
}
XFCLOSE(s);
}
}
Expand Down Expand Up @@ -344,11 +358,23 @@ int wolfCLU_sign_data_ecc(byte* data, char* out, word32 fSz, char* privKey,
}
}
if (ret == 0) {
XFSEEK(privKeyFile, 0, SEEK_END);
if (XFSEEK(privKeyFile, 0, SEEK_END) != 0) {
wolfCLU_LogError("Failed to seek to end of file.");
ret = WOLFCLU_FATAL_ERROR;
}
}
if (ret == 0) {
privFileSz = (int)XFTELL(privKeyFile);
keyBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (keyBuf == NULL) {
ret = MEMORY_E;
if (privFileSz > 0 && privFileSz <= (MAX_ECC_BITS_NEEDED / 8 * 16)) {
keyBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT,
DYNAMIC_TYPE_TMP_BUFFER);
if (keyBuf == NULL) {
ret = MEMORY_E;
}
}
else {
wolfCLU_LogError("Incorrect private key file size: %d", privFileSz);
ret = WOLFCLU_FATAL_ERROR;
}
}
if (ret == 0) {
Expand Down Expand Up @@ -431,7 +457,9 @@ int wolfCLU_sign_data_ecc(byte* data, char* out, word32 fSz, char* privKey,
ret = BAD_FUNC_ARG;
}
else {
XFWRITE(outBuf, 1, outLen, s);
if ((int)XFWRITE(outBuf, 1, outLen, s) <= 0) {
ret = OUTPUT_FILE_ERROR;
}
XFCLOSE(s);
}
}
Expand Down Expand Up @@ -506,11 +534,23 @@ int wolfCLU_sign_data_ed25519 (byte* data, char* out, word32 fSz, char* privKey,
}
}
if (ret == 0) {
XFSEEK(privKeyFile, 0, SEEK_END);
if (XFSEEK(privKeyFile, 0, SEEK_END) != 0) {
wolfCLU_LogError("Failed to seek to end of file.");
ret = WOLFCLU_FATAL_ERROR;
}
}
if (ret == 0) {
privFileSz = (int)XFTELL(privKeyFile);
keyBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (keyBuf == NULL) {
ret = MEMORY_E;
if (privFileSz > 0 && privFileSz <= (ED25519_PRV_KEY_SIZE * 16)) {
keyBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT,
DYNAMIC_TYPE_TMP_BUFFER);
if (keyBuf == NULL) {
ret = MEMORY_E;
}
}
else {
wolfCLU_LogError("Incorrect private key file size: %d", privFileSz);
ret = WOLFCLU_FATAL_ERROR;
}
}
if (ret == 0) {
Expand Down Expand Up @@ -582,7 +622,9 @@ int wolfCLU_sign_data_ed25519 (byte* data, char* out, word32 fSz, char* privKey,
ret = BAD_FUNC_ARG;
}
else {
XFWRITE(outBuf, 1, outLen, s);
if ((int)XFWRITE(outBuf, 1, outLen, s) <= 0) {
ret = OUTPUT_FILE_ERROR;
}
XFCLOSE(s);
}
}
Expand Down Expand Up @@ -618,16 +660,18 @@ int wolfCLU_sign_data_dilithium (byte* data, char* out, word32 dataSz, char* pri
{
#ifdef HAVE_DILITHIUM
int ret = 0;
int privFileSz = 0;
word32 index = 0;

XFILE privKeyFile = NULL;
byte* privBuf = NULL;
int privFileSz = 0;

word32 privBufSz = 0;
word32 index = 0;
byte* outBuf = NULL;
word32 outBufSz = 0;

WC_RNG rng;
XMEMSET(&rng, 0, sizeof(rng));


#ifdef WOLFSSL_SMALL_STACK
dilithium_key* key;
Expand All @@ -641,6 +685,7 @@ int wolfCLU_sign_data_dilithium (byte* data, char* out, word32 dataSz, char* pri
#endif

/* zero before init for defensive security */
XMEMSET(&rng, 0, sizeof(rng));
XMEMSET(key, 0, sizeof(dilithium_key));

/* init the dilithium key */
Expand All @@ -650,146 +695,137 @@ int wolfCLU_sign_data_dilithium (byte* data, char* out, word32 dataSz, char* pri
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return WOLFCLU_FAILURE;
return ret;
}

if (wc_InitRng(&rng) != 0) {
wolfCLU_LogError("Failed to initialize rng.\nRET: %d", ret);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return WOLFCLU_FAILURE;
/* initialize RNG */
if (ret == 0) {
ret = wc_InitRng(&rng);
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if (ret != 0) {
wolfCLU_LogError("Failed to initialize rng.\nRET: %d", ret);
}
}

/* open and read private key */
privKeyFile = XFOPEN(privKey, "rb");
if (privKeyFile == NULL) {
wolfCLU_LogError("Faild to open Private key FILE.");
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return WOLFCLU_FATAL_ERROR;
if (ret == 0) {
privKeyFile = XFOPEN(privKey, "rb");
if (privKeyFile == NULL) {
wolfCLU_LogError("Failed to open Private key FILE.");
ret = BAD_FUNC_ARG;
}
}

XFSEEK(privKeyFile, 0, SEEK_END);
privFileSz = (int)XFTELL(privKeyFile);
privBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (privBuf == NULL) {
XFCLOSE(privKeyFile);
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return MEMORY_E;
if (ret == 0) {
if (XFSEEK(privKeyFile, 0, SEEK_END) != 0) {
wolfCLU_LogError("Failed to seek to end of file.");
ret = WOLFCLU_FATAL_ERROR;
}
if (ret == 0) {
privFileSz = (int)XFTELL(privKeyFile);
if (privFileSz > 0 &&
privFileSz <= DILITHIUM_MAX_BOTH_KEY_PEM_SIZE) {
privBuf = (byte*)XMALLOC(privFileSz+1, HEAP_HINT,
DYNAMIC_TYPE_TMP_BUFFER);
if (privBuf == NULL) {
ret = MEMORY_E;
}
} else {
wolfCLU_LogError("Incorrect private key file size: %d",
privFileSz);
ret = WOLFCLU_FATAL_ERROR;
}
}
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}

XMEMSET(privBuf, 0, privFileSz+1);
privBufSz = privFileSz;
XFSEEK(privKeyFile, 0, SEEK_SET);
if (XFREAD(privBuf, 1, privBufSz, privKeyFile) != privBufSz) {
wolfCLU_Log(WOLFCLU_L0, "incorecct size: %d", privFileSz);
XFREE(privBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return WOLFCLU_FATAL_ERROR;
if (ret == 0) {
XMEMSET(privBuf, 0, privFileSz+1);
privBufSz = privFileSz;
if (XFSEEK(privKeyFile, 0, SEEK_SET) != 0 ||
(int)XFREAD(privBuf, 1, privFileSz, privKeyFile) != privFileSz) {
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wolfCLU_LogError("Failed to read private key file.");
ret = WOLFCLU_FATAL_ERROR;
}
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}
XFCLOSE(privKeyFile);

/* convert PEM to DER if necessary */
if (inForm == PEM_FORM) {
if (inForm == PEM_FORM && ret == 0) {
ret = wolfCLU_KeyPemToDer(&privBuf, privFileSz, 0);
if (ret < 0) {
wolfCLU_LogError("Failed to convert PEM to DER.\nRET: %d", ret);
XFREE(privBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}
else {
privFileSz = ret;
/* update privBuf and privFileSz with the converted DER data */
privBufSz = privFileSz = ret;
ret = 0;
}
}

/* retrieving private key and staoring in the Dilithium key */
ret = wc_Dilithium_PrivateKeyDecode(privBuf, &index, key, privBufSz);
XFREE(privBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (ret != 0) {
wolfCLU_LogError("Failed to decode private key.\nRET: %d", ret);
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
/* retrieving private key and storing in the Dilithium key */
if (ret == 0) {
ret = wc_Dilithium_PrivateKeyDecode(privBuf, &index, key, privBufSz);
if (ret != 0) {
wolfCLU_LogError("Failed to decode private key.\nRET: %d", ret);
}
}

/* malloc signature buffer */
outBufSz = wc_dilithium_sig_size(key);
outBuf = (byte*)XMALLOC(outBufSz, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (outBuf == NULL) {
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return MEMORY_E;
if (ret == 0) {
outBufSz = wc_dilithium_sig_size(key);
outBuf = (byte*)XMALLOC(outBufSz, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
if (outBuf == NULL) {
ret = MEMORY_E;
wolfCLU_LogError("Failed to allocate signature"
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" buffer.\nRET: %d", ret);
}
}

/* sign the message usign Dilithium private key. Note that the context is
* empty. This is for interoperability. */
ret = wc_dilithium_sign_ctx_msg(NULL, 0, data, dataSz, outBuf, &outBufSz,
key, &rng);
if (ret != 0) {
wolfCLU_LogError("Failed to sign data with Dilithium private key.\nRET: %d", ret);
XFREE(outBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
if (ret == 0) {
ret = wc_dilithium_sign_ctx_msg(NULL, 0, data, dataSz, outBuf,
&outBufSz, key, &rng);
if (ret != 0) {
wolfCLU_LogError("Failed to sign data with"
" Dilithium private key.\nRET: %d", ret);
}
}
else {

if (ret == 0) {
XFILE outFile;
outFile = XFOPEN(out, "wb");

if (outFile == NULL) {
wolfCLU_LogError("Failed to open output file %s", out);
XFREE(outBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
wc_FreeRng(&rng);
wc_dilithium_free(key);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return BAD_FUNC_ARG;
}
XFWRITE(outBuf, 1, outBufSz, outFile);
XFCLOSE(outFile);
ret = BAD_FUNC_ARG;
} else {
if ((int)XFWRITE(outBuf, 1, outBufSz, outFile) <= 0) {
ret = OUTPUT_FILE_ERROR;
}
XFCLOSE(outFile);
}
}

XFREE(outBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
wc_FreeRng(&rng);
wc_dilithium_free(key);
/* cleanup allocated resources */
if (privKeyFile != NULL)
XFCLOSE(privKeyFile);

if (privBuf != NULL) {
XFREE(privBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
}

if (outBuf != NULL) {
XFREE(outBuf, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
}

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wc_dilithium_free(key);
wc_FreeRng(&rng);
#ifdef WOLFSSL_SMALL_STACK
XFREE(key, HEAP_HINT, DYNAMIC_TYPE_TMP_BUFFER);
#endif

return WOLFCLU_SUCCESS;
/* expected ret == WOLFCLU_SUCCESS */
return (ret >= 0) ? WOLFCLU_SUCCESS : ret;
#else
(void)data;
(void)out;
(void)dataSz;
(void) privKey;
(void)privKey;
(void)inForm;

return NOT_COMPILED_IN;
Expand Down
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