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Improve integer-type hygiene in bignum code.

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In many places I was using an 'unsigned int', or an implicit int by
virtue of writing an undecorated integer literal, where what was
really wanted was a BignumInt. In particular, this substitution breaks
in any situation where BignumInt is _larger_ than unsigned - which it
is shortly about to be.
This commit is contained in:
Simon Tatham 2015-06-08 19:23:48 +01:00
parent 0aa92c8fa2
commit e28b35b0a3
2 changed files with 17 additions and 14 deletions
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25
sshbn.c
View File

@ -515,7 +515,7 @@ static void monty_reduce(BignumInt *x, const BignumInt *n,
} }
static void internal_add_shifted(BignumInt *number, static void internal_add_shifted(BignumInt *number,
unsigned n, int shift) BignumInt n, int shift)
{ {
int word = 1 + (shift / BIGNUM_INT_BITS); int word = 1 + (shift / BIGNUM_INT_BITS);
int bshift = shift % BIGNUM_INT_BITS; int bshift = shift % BIGNUM_INT_BITS;
@ -546,8 +546,7 @@ static void internal_mod(BignumInt *a, int alen,
BignumInt *m, int mlen, BignumInt *m, int mlen,
BignumInt *quot, int qshift) BignumInt *quot, int qshift)
{ {
BignumInt m0, m1; BignumInt m0, m1, h;
unsigned int h;
int i, k; int i, k;
m0 = m[0]; m0 = m[0];
@ -559,7 +558,7 @@ static void internal_mod(BignumInt *a, int alen,
for (i = 0; i <= alen - mlen; i++) { for (i = 0; i <= alen - mlen; i++) {
BignumDblInt t; BignumDblInt t;
unsigned int q, r, c, ai1; BignumInt q, r, c, ai1;
if (i == 0) { if (i == 0) {
h = 0; h = 0;
@ -614,7 +613,7 @@ static void internal_mod(BignumInt *a, int alen,
for (k = mlen - 1; k >= 0; k--) { for (k = mlen - 1; k >= 0; k--) {
t = MUL_WORD(q, m[k]); t = MUL_WORD(q, m[k]);
t += c; t += c;
c = (unsigned)(t >> BIGNUM_INT_BITS); c = (BignumInt)(t >> BIGNUM_INT_BITS);
if ((BignumInt) t > a[i + k]) if ((BignumInt) t > a[i + k])
c++; c++;
a[i + k] -= (BignumInt) t; a[i + k] -= (BignumInt) t;
@ -697,7 +696,7 @@ Bignum modpow_simple(Bignum base_in, Bignum exp, Bignum mod)
/* Skip leading zero bits of exp. */ /* Skip leading zero bits of exp. */
i = 0; i = 0;
j = BIGNUM_INT_BITS-1; j = BIGNUM_INT_BITS-1;
while (i < (int)exp[0] && (exp[exp[0] - i] & (1 << j)) == 0) { while (i < (int)exp[0] && (exp[exp[0] - i] & ((BignumInt)1 << j)) == 0) {
j--; j--;
if (j < 0) { if (j < 0) {
i++; i++;
@ -710,7 +709,7 @@ Bignum modpow_simple(Bignum base_in, Bignum exp, Bignum mod)
while (j >= 0) { while (j >= 0) {
internal_mul(a + mlen, a + mlen, b, mlen, scratch); internal_mul(a + mlen, a + mlen, b, mlen, scratch);
internal_mod(b, mlen * 2, m, mlen, NULL, 0); internal_mod(b, mlen * 2, m, mlen, NULL, 0);
if ((exp[exp[0] - i] & (1 << j)) != 0) { if ((exp[exp[0] - i] & ((BignumInt)1 << j)) != 0) {
internal_mul(b + mlen, n, a, mlen, scratch); internal_mul(b + mlen, n, a, mlen, scratch);
internal_mod(a, mlen * 2, m, mlen, NULL, 0); internal_mod(a, mlen * 2, m, mlen, NULL, 0);
} else { } else {
@ -847,7 +846,7 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod)
/* Skip leading zero bits of exp. */ /* Skip leading zero bits of exp. */
i = 0; i = 0;
j = BIGNUM_INT_BITS-1; j = BIGNUM_INT_BITS-1;
while (i < (int)exp[0] && (exp[exp[0] - i] & (1 << j)) == 0) { while (i < (int)exp[0] && (exp[exp[0] - i] & ((BignumInt)1 << j)) == 0) {
j--; j--;
if (j < 0) { if (j < 0) {
i++; i++;
@ -860,7 +859,7 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod)
while (j >= 0) { while (j >= 0) {
internal_mul(a + len, a + len, b, len, scratch); internal_mul(a + len, a + len, b, len, scratch);
monty_reduce(b, n, mninv, scratch, len); monty_reduce(b, n, mninv, scratch, len);
if ((exp[exp[0] - i] & (1 << j)) != 0) { if ((exp[exp[0] - i] & ((BignumInt)1 << j)) != 0) {
internal_mul(b + len, x, a, len, scratch); internal_mul(b + len, x, a, len, scratch);
monty_reduce(a, n, mninv, scratch, len); monty_reduce(a, n, mninv, scratch, len);
} else { } else {
@ -1139,7 +1138,8 @@ Bignum bignum_from_bytes(const unsigned char *data, int nbytes)
result[i] = 0; result[i] = 0;
for (i = nbytes; i--;) { for (i = nbytes; i--;) {
unsigned char byte = *data++; unsigned char byte = *data++;
result[1 + i / BIGNUM_INT_BYTES] |= byte << (8*i % BIGNUM_INT_BITS); result[1 + i / BIGNUM_INT_BYTES] |=
(BignumInt)byte << (8*i % BIGNUM_INT_BITS);
} }
while (result[0] > 1 && result[result[0]] == 0) while (result[0] > 1 && result[result[0]] == 0)
@ -1161,7 +1161,8 @@ Bignum bignum_from_bytes_le(const unsigned char *data, int nbytes)
result[i] = 0; result[i] = 0;
for (i = 0; i < nbytes; ++i) { for (i = 0; i < nbytes; ++i) {
unsigned char byte = *data++; unsigned char byte = *data++;
result[1 + i / BIGNUM_INT_BYTES] |= byte << (8*i % BIGNUM_INT_BITS); result[1 + i / BIGNUM_INT_BYTES] |=
(BignumInt)byte << (8*i % BIGNUM_INT_BITS);
} }
while (result[0] > 1 && result[result[0]] == 0) while (result[0] > 1 && result[result[0]] == 0)
@ -1314,7 +1315,7 @@ void bignum_set_bit(Bignum bn, int bitnum, int value)
abort(); /* beyond the end */ abort(); /* beyond the end */
else { else {
int v = bitnum / BIGNUM_INT_BITS + 1; int v = bitnum / BIGNUM_INT_BITS + 1;
int mask = 1 << (bitnum % BIGNUM_INT_BITS); BignumInt mask = (BignumInt)1 << (bitnum % BIGNUM_INT_BITS);
if (value) if (value)
bn[v] |= mask; bn[v] |= mask;
else else

6
sshccp.c
View File

@ -198,7 +198,8 @@ static void bigval_import_le(bigval *r, const void *vdata, int len)
int i; int i;
bigval_clear(r); bigval_clear(r);
for (i = 0; i < len; i++) for (i = 0; i < len; i++)
r->w[i / BIGNUM_INT_BYTES] |= data[i] << (8 * (i % BIGNUM_INT_BYTES)); r->w[i / BIGNUM_INT_BYTES] |=
(BignumInt)data[i] << (8 * (i % BIGNUM_INT_BYTES));
} }
static void bigval_export_le(const bigval *r, void *vdata, int len) static void bigval_export_le(const bigval *r, void *vdata, int len)
@ -951,7 +952,8 @@ static void poly1305_feed_chunk(struct poly1305 *ctx,
{ {
bigval c; bigval c;
bigval_import_le(&c, chunk, len); bigval_import_le(&c, chunk, len);
c.w[len / BIGNUM_INT_BYTES] |= 1 << (8 * (len % BIGNUM_INT_BYTES)); c.w[len / BIGNUM_INT_BYTES] |=
(BignumInt)1 << (8 * (len % BIGNUM_INT_BYTES));
bigval_add(&c, &c, &ctx->h); bigval_add(&c, &c, &ctx->h);
bigval_mul_mod_p(&ctx->h, &c, &ctx->r); bigval_mul_mod_p(&ctx->h, &c, &ctx->r);
} }