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Use sizeof for SP digit memory operations on targets where a char is wider than 8 bits #12094

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Use sizeof for SP digit memory operations on targets where a char is wider than 8 bits #12094

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2 changes: 1 addition & 1 deletion tests/unit-mcdc/test_dh_fault_whitebox.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@
* (b) size-capacity rows: sp_int is a fixed SP_INT_DIGITS-digit struct
* (SP_INT_BITS=4096 here); mp_read_unsigned_bin()/sp_exptmod() reject
* inputs that do not fit *by construction* (sp_read_unsigned_bin: inSz
* > a->size*SP_WORD_SIZEOF; sp_exptmod_ex: m->used*2 >= SP_INT_DIGITS).
* > a->size*SP_WORD_OCTETS; sp_exptmod_ex: m->used*2 >= SP_INT_DIGITS).
* Passing an oversized buffer (here: 2000 zero bytes, always over the
* ~1024-1032 byte capacity regardless of 32/64-bit sp_int digits) or a
* modulus bigger than SP_INT_BITS deterministically fails that call
Expand Down
37 changes: 20 additions & 17 deletions wolfcrypt/src/sp_int.c
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Expand Up @@ -5426,7 +5426,7 @@ void sp_forcezero(sp_int* a)
/* Zeroize when a valid pointer passed in. */
if (a != NULL) {
/* Ensure all data zeroized - data not zeroed when used decreases. */
ForceZero(a->dp, a->size * (word32)SP_WORD_SIZEOF);
ForceZero(a->dp, a->size * (word32)sizeof(sp_int_digit));
/* Set back to zero. */
#ifdef HAVE_WOLF_BIGINT
/* Zeroize the raw data as well. */
Expand All @@ -5453,7 +5453,7 @@ static void _sp_copy(const sp_int* a, sp_int* r)
r->dp[0] = 0;
}
else {
XMEMCPY(r->dp, a->dp, a->used * (word32)SP_WORD_SIZEOF);
XMEMCPY(r->dp, a->dp, a->used * (word32)sizeof(sp_int_digit));
}
/* Set number of used words in result. */
r->used = a->used;/* // NOLINT(clang-analyzer-core.uninitialized.Assign) */
Expand Down Expand Up @@ -6217,7 +6217,7 @@ int sp_set_bit(sp_int* a, int i)
* check below rather than wrapping. */
int wi = (i < 0) ? 0 : (i >> SP_WORD_SHIFT);

#if SP_INT_DIGITS < (65536 / SP_WORD_SIZEOF)
#if SP_INT_DIGITS < (65536 / SP_WORD_OCTETS)
/* Check bit index isn't bigger than maximum allowed. */
if (i > SP_INT_DIGITS * SP_WORD_SIZE) {
err = MP_VAL;
Expand Down Expand Up @@ -8584,9 +8584,9 @@ int sp_lshd(sp_int* a, int s)
}
if (err == MP_OKAY) {
/* Move up digits. */
XMEMMOVE(a->dp + s, a->dp, a->used * (word32)SP_WORD_SIZEOF);
XMEMMOVE(a->dp + s, a->dp, a->used * (word32)sizeof(sp_int_digit));
/* Back fill with zeros. */
XMEMSET(a->dp, 0, (size_t)s * SP_WORD_SIZEOF);
XMEMSET(a->dp, 0, (size_t)s * sizeof(sp_int_digit));
/* Update used. */
a->used = (sp_size_t)(a->used + s);
/* Remove leading zeros. */
Expand Down Expand Up @@ -8652,13 +8652,14 @@ static int sp_lshb(sp_int* a, int n)
/* Only digits to move and ensure not zero. */
else if (s > 0) {
/* Move up digits. */
XMEMMOVE(a->dp + s, a->dp, a->used * (word32)SP_WORD_SIZEOF);
XMEMMOVE(a->dp + s, a->dp,
a->used * (word32)sizeof(sp_int_digit));
}

/* Update used digit count. */
a->used = (sp_size_t)(a->used + s);
/* Back fill with zeros. */
XMEMSET(a->dp, 0, (word32)SP_WORD_SIZEOF * s);
XMEMSET(a->dp, 0, (word32)sizeof(sp_int_digit) * s);
}
}

Expand Down Expand Up @@ -8735,10 +8736,12 @@ int sp_rshb(const sp_int* a, int n, sp_int* r)
r->used = (sp_size_t)(a->used - i);
/* Move digits down. */
if (r == a) {
XMEMMOVE(r->dp, r->dp + i, (word32)SP_WORD_SIZEOF * r->used);
XMEMMOVE(r->dp, r->dp + i,
(word32)sizeof(sp_int_digit) * r->used);
}
else {
XMEMCPY(r->dp, a->dp + i, (word32)SP_WORD_SIZEOF * r->used);
XMEMCPY(r->dp, a->dp + i,
(word32)sizeof(sp_int_digit) * r->used);
}
}
else {
Expand Down Expand Up @@ -15007,7 +15010,7 @@ int sp_mod_2d(const sp_int* a, int e, sp_int* r)
/* Copy a into r if not same pointer. */
if (a != r) {
sp_size_t cnt = (a->used < digits) ? a->used : digits;
XMEMCPY(r->dp, a->dp, cnt * (word32)SP_WORD_SIZEOF);
XMEMCPY(r->dp, a->dp, cnt * (word32)sizeof(sp_int_digit));
r->used = a->used;
#ifdef WOLFSSL_SP_INT_NEGATIVE
r->sign = a->sign;
Expand Down Expand Up @@ -18343,7 +18346,7 @@ int sp_read_unsigned_bin(sp_int* a, const byte* in, word32 inSz)
}

/* Check a has enough space for number. */
if ((err == MP_OKAY) && (inSz > (word32)a->size * SP_WORD_SIZEOF)) {
if ((err == MP_OKAY) && (inSz > (word32)a->size * SP_WORD_OCTETS)) {
err = MP_VAL;
}

Expand All @@ -18352,18 +18355,18 @@ int sp_read_unsigned_bin(sp_int* a, const byte* in, word32 inSz)
int i;
int j = 0;

a->used = (sp_size_t)((inSz + SP_WORD_SIZEOF - 1) / SP_WORD_SIZEOF);
a->used = (sp_size_t)((inSz + SP_WORD_OCTETS - 1) / SP_WORD_OCTETS);

#if defined(BIG_ENDIAN_ORDER) && !defined(WOLFSSL_SP_INT_DIGIT_ALIGN)
/* Data endian matches representation of number.
* Directly copy if we don't have alignment issues.
*/
for (i = (int)(inSz-1); i > SP_WORD_SIZEOF-1; i -= SP_WORD_SIZEOF) {
a->dp[j++] = *(sp_int_digit*)(in + i - (SP_WORD_SIZEOF - 1));
for (i = (int)(inSz-1); i > SP_WORD_OCTETS-1; i -= SP_WORD_OCTETS) {
a->dp[j++] = *(sp_int_digit*)(in + i - (SP_WORD_OCTETS - 1));
}
#else
/* Construct digit from required number of bytes. */
for (i = (int)(inSz-1); i >= SP_WORD_SIZEOF - 1; i -= SP_WORD_SIZEOF) {
for (i = (int)(inSz-1); i >= SP_WORD_OCTETS - 1; i -= SP_WORD_OCTETS) {
a->dp[j] = ((sp_int_digit)in[i - 0] << 0)
#if SP_WORD_SIZE >= 16
| ((sp_int_digit)in[i - 1] << 8)
Expand Down Expand Up @@ -18554,7 +18557,7 @@ int sp_to_unsigned_bin_len_ct(const sp_int* a, byte* out, int outSz)

d = a->dp[i];
/* Place each byte of a digit into the buffer. */
for (b = 0; (j >= 0) && (b < SP_WORD_SIZEOF); b++) {
for (b = 0; (j >= 0) && (b < SP_WORD_OCTETS); b++) {
out[j--] = (byte)(d & mask);
d >>= 8;
}
Expand Down Expand Up @@ -19203,7 +19206,7 @@ int sp_rand_prime(sp_int* r, int len, WC_RNG* rng, void* heap)
}

/* Get number of digits required to handle required number of bytes. */
digits = ((unsigned int)len + SP_WORD_SIZEOF - 1) / SP_WORD_SIZEOF;
digits = ((unsigned int)len + SP_WORD_OCTETS - 1) / SP_WORD_OCTETS;
/* Ensure result has space. */
if (r->size < digits) {
err = MP_VAL;
Expand Down
2 changes: 1 addition & 1 deletion wolfcrypt/test/test.c
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Expand Up @@ -93353,7 +93353,7 @@ static wc_test_ret_t mp_test_param(mp_int* a, mp_int* b, mp_int* r, WC_RNG* rng)
ret = mp_read_unsigned_bin(a, NULL, sizeof(buffer));
if (ret != WC_NO_ERR_TRACE(MP_VAL))
return WC_TEST_RET_ENC_EC(ret);
ret = mp_read_unsigned_bin(a, buffer, SP_INT_DIGITS * SP_WORD_SIZEOF + 1);
ret = mp_read_unsigned_bin(a, buffer, SP_INT_DIGITS * SP_WORD_OCTETS + 1);
if (ret != WC_NO_ERR_TRACE(MP_VAL))
return WC_TEST_RET_ENC_EC(ret);

Expand Down
20 changes: 13 additions & 7 deletions wolfssl/wolfcrypt/sp_int.h
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Expand Up @@ -291,8 +291,14 @@ extern "C" {
#endif
#endif

/* SP_WORD_OCTETS: number of octets (8-bit units) in an SP digit.
* Use for counts of octets in encoded data (e.g. sp_read_unsigned_bin()),
* XALIGNED() and preprocessor conditionals - must be an integer literal.
* Not the size of a digit in memory where CHAR_BIT != 8 (e.g. TI C28x) - use
* sizeof(sp_int_digit) for memory operations (XMEMCPY, XMEMSET, ForceZero).
*/
#if SP_WORD_SIZE == 8
#define SP_WORD_SIZEOF 1
#define SP_WORD_OCTETS 1

typedef sp_uint8 sp_int_digit;
typedef sp_int8 sp_int_sdigit;
Expand All @@ -301,7 +307,7 @@ extern "C" {

#define SP_MASK 0xffU
#elif SP_WORD_SIZE == 16
#define SP_WORD_SIZEOF 2
#define SP_WORD_OCTETS 2

typedef sp_uint16 sp_int_digit;
typedef sp_int16 sp_int_sdigit;
Expand All @@ -310,7 +316,7 @@ extern "C" {

#define SP_MASK 0xffffU
#elif SP_WORD_SIZE == 32
#define SP_WORD_SIZEOF 4
#define SP_WORD_OCTETS 4

typedef sp_uint32 sp_int_digit;
typedef sp_int32 sp_int_sdigit;
Expand All @@ -319,7 +325,7 @@ extern "C" {

#define SP_MASK 0xffffffffU
#elif SP_WORD_SIZE == 64
#define SP_WORD_SIZEOF 8
#define SP_WORD_OCTETS 8

typedef sp_uint64 sp_int_digit;
typedef sp_int64 sp_int_sdigit;
Expand Down Expand Up @@ -976,7 +982,7 @@ while (0)
#define WOLF_BIGINT_DEFINED
#endif

#if SP_INT_DIGITS < (65536 / SP_WORD_SIZEOF)
#if SP_INT_DIGITS < (65536 / SP_WORD_OCTETS)
/* Type for number of digits. */
typedef word16 sp_size_t;
#else
Expand Down Expand Up @@ -1010,7 +1016,7 @@ typedef struct sp_int {
struct WC_BIGINT raw;
#endif
/** Data of number. */
XALIGNED(SP_WORD_SIZEOF) sp_int_digit dp[SP_INT_DIGITS];
XALIGNED(SP_WORD_OCTETS) sp_int_digit dp[SP_INT_DIGITS];
} sp_int;

typedef struct sp_int_minimal {
Expand All @@ -1027,7 +1033,7 @@ typedef struct sp_int_minimal {
struct WC_BIGINT raw;
#endif
/** First digit of number. */
XALIGNED(SP_WORD_SIZEOF) sp_int_digit dp[1];
XALIGNED(SP_WORD_OCTETS) sp_int_digit dp[1];
} sp_int_minimal;

/* MP_INT_SIZEOF_DIGITS() requires that sizeof(sp_int) is a multiple of
Expand Down
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