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RSA-PSS: Handle edge case with encoding message to hash

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When the key is small relative to the digest (1024-bit key, 64-byte
hash, 61-byte salt length), the internal message to hash is larger than
the output size.
Allocate a buffer for the message when this happens.
This commit is contained in:
Sean Parkinson
2020-10-27 12:39:06 +10:00
parent 2ebb47ec32
commit fb2288c46d
1 changed files with 25 additions and 13 deletions
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38
wolfcrypt/src/rsa.c
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@ -1116,12 +1116,13 @@ static int RsaPad_PSS(const byte* input, word32 inputLen, byte* pkcsBlock,
int hLen, i, o, maskLen, hiBits;
byte* m;
byte* s;
#if defined(WOLFSSL_NO_MALLOC) && !defined(WOLFSSL_STATIC_MEMORY)
byte msg[RSA_MAX_SIZE/8 + RSA_PSS_PAD_SZ];
#else
byte* msg = NULL;
#endif
#if defined(WOLFSSL_PSS_LONG_SALT) || defined(WOLFSSL_PSS_SALT_LEN_DISCOVER)
#if defined(WOLFSSL_NO_MALLOC) && !defined(WOLFSSL_STATIC_MEMORY)
byte salt[RSA_MAX_SIZE/8 + RSA_PSS_PAD_SZ];
#else
byte* salt = NULL;
#endif
byte* salt;
#else
byte salt[WC_MAX_DIGEST_SIZE];
#endif
@ -1184,13 +1185,13 @@ static int RsaPad_PSS(const byte* input, word32 inputLen, byte* pkcsBlock,
#if defined(WOLFSSL_PSS_LONG_SALT) || defined(WOLFSSL_PSS_SALT_LEN_DISCOVER)
#if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
salt = (byte*)XMALLOC(RSA_PSS_PAD_SZ + inputLen + saltLen, heap,
msg = (byte*)XMALLOC(RSA_PSS_PAD_SZ + inputLen + saltLen, heap,
DYNAMIC_TYPE_RSA_BUFFER);
if (salt == NULL) {
if (msg == NULL) {
return MEMORY_E;
}
#endif
s = m = salt;
salt = s = m = msg;
XMEMSET(m, 0, RSA_PSS_PAD_SZ);
m += RSA_PSS_PAD_SZ;
XMEMCPY(m, input, inputLen);
@ -1203,7 +1204,20 @@ static int RsaPad_PSS(const byte* input, word32 inputLen, byte* pkcsBlock,
}
}
#else
s = m = pkcsBlock;
if (pkcsBlockLen < RSA_PSS_PAD_SZ + inputLen + saltLen) {
#if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
msg = (byte*)XMALLOC(RSA_PSS_PAD_SZ + inputLen + saltLen, heap,
DYNAMIC_TYPE_RSA_BUFFER);
if (msg == NULL) {
return MEMORY_E;
}
#endif
m = msg;
}
else {
m = pkcsBlock;
}
s = m;
XMEMSET(m, 0, RSA_PSS_PAD_SZ);
m += RSA_PSS_PAD_SZ;
XMEMCPY(m, input, inputLen);
@ -1240,13 +1254,11 @@ static int RsaPad_PSS(const byte* input, word32 inputLen, byte* pkcsBlock,
}
}
#if defined(WOLFSSL_PSS_LONG_SALT) || defined(WOLFSSL_PSS_SALT_LEN_DISCOVER)
#if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
if (salt != NULL) {
XFREE(salt, heap, DYNAMIC_TYPE_RSA_BUFFER);
if (msg != NULL) {
XFREE(msg, heap, DYNAMIC_TYPE_RSA_BUFFER);
}
#endif
#endif
return ret;
}
#endif /* WC_RSA_PSS */