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annotate libtommath/bn_mp_mod.c @ 1597:8f7b6f75aa58

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fix uninitialised memory in fuzzer codepath
author Matt Johnston <matt@ucc.asn.au>
date Tue, 06 Mar 2018 22:02:19 +0800
parents 8bba51a55704
children f52919ffd3b1
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1 #include <tommath_private.h>
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2 #ifdef BN_MP_MOD_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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4 *
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5 * LibTomMath is a library that provides multiple-precision
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6 * integer arithmetic as well as number theoretic functionality.
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7 *
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8 * The library was designed directly after the MPI library by
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9 * Michael Fromberger but has been written from scratch with
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10 * additional optimizations in place.
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11 *
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12 * The library is free for all purposes without any express
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13 * guarantee it works.
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14 *
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15 * Tom St Denis, [email protected], http://libtom.org
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16 */
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17
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18 /* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */
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19 int
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20 mp_mod (mp_int * a, mp_int * b, mp_int * c)
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21 {
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22 mp_int t;
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23 int res;
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24
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4fbf9a7556ed Use mp_init_size() to avoid some mp_grow()s
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25 if ((res = mp_init_size (&t, b->used)) != MP_OKAY) {
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26 return res;
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27 }
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29 if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) {
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30 mp_clear (&t);
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31 return res;
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32 }
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33
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34 if ((mp_iszero(&t) != MP_NO) || (t.sign == b->sign)) {
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35 res = MP_OKAY;
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36 mp_exch (&t, c);
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37 } else {
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38 res = mp_add (b, &t, c);
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39 }
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41 mp_clear (&t);
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42 return res;
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43 }
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44 #endif
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45
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46 /* ref: $Format:%D$ */
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47 /* git commit: $Format:%H$ */
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48 /* commit time: $Format:%ai$ */