Merge pull request #1018 from dgarske/fix_tfm_rusb_max
Fix for fast math `fp_read_unsigned_bin` function to check max size
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4491102eed
@ -1868,9 +1868,22 @@ void fp_montgomery_reduce(fp_int *a, fp_int *m, fp_digit mp)
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void fp_read_unsigned_bin(fp_int *a, const unsigned char *b, int c)
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{
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#if defined(ALT_ECC_SIZE) || defined(HAVE_WOLF_BIGINT)
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const word32 maxC = (a->size * sizeof(fp_digit));
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#else
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const word32 maxC = (FP_SIZE * sizeof(fp_digit));
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#endif
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/* zero the int */
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fp_zero (a);
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/* if input b excess max, then truncate */
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if (c > 0 && (word32)c > maxC) {
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int excess = (c - maxC);
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c -= excess;
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b += excess;
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}
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/* If we know the endianness of this architecture, and we're using
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32-bit fp_digits, we can optimize this */
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#if (defined(LITTLE_ENDIAN_ORDER) || defined(BIG_ENDIAN_ORDER)) && \
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@ -1882,11 +1895,6 @@ void fp_read_unsigned_bin(fp_int *a, const unsigned char *b, int c)
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{
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unsigned char *pd = (unsigned char *)a->dp;
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if ((unsigned)c > (FP_SIZE * sizeof(fp_digit))) {
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int excess = c - (FP_SIZE * sizeof(fp_digit));
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c -= excess;
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b += excess;
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}
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a->used = (c + sizeof(fp_digit) - 1)/sizeof(fp_digit);
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/* read the bytes in */
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#ifdef BIG_ENDIAN_ORDER
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@ -1913,7 +1921,10 @@ void fp_read_unsigned_bin(fp_int *a, const unsigned char *b, int c)
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for (; c > 0; c--) {
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fp_mul_2d (a, 8, a);
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a->dp[0] |= *b++;
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a->used += 1;
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if (a->used == 0) {
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a->used = 1;
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}
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}
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#endif
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fp_clamp (a);
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