Bug Summary

File:ecc-mod.c
Location:line 104, column 16
Description:The left operand of '<<' is a garbage value

Annotated Source Code

1/* ecc-mod.c
2
3 Copyright (C) 2013 Niels Möller
4
5 This file is part of GNU Nettle.
6
7 GNU Nettle is free software: you can redistribute it and/or
8 modify it under the terms of either:
9
10 * the GNU Lesser General Public License as published by the Free
11 Software Foundation; either version 3 of the License, or (at your
12 option) any later version.
13
14 or
15
16 * the GNU General Public License as published by the Free
17 Software Foundation; either version 2 of the License, or (at your
18 option) any later version.
19
20 or both in parallel, as here.
21
22 GNU Nettle is distributed in the hope that it will be useful,
23 but WITHOUT ANY WARRANTY; without even the implied warranty of
24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 General Public License for more details.
26
27 You should have received copies of the GNU General Public License and
28 the GNU Lesser General Public License along with this program. If
29 not, see http://www.gnu.org/licenses/.
30*/
31
32/* Development of Nettle's ECC support was funded by the .SE Internet Fund. */
33
34#if HAVE_CONFIG_H1
35# include "config.h"
36#endif
37
38#include <assert.h>
39
40#include "ecc-internal.h"
41
42/* Computes r mod m, input 2*m->size, output m->size. */
43void
44ecc_mod_nettle_ecc_mod (const struct ecc_modulo *m, mp_limb_t *rp)
45{
46 mp_limb_t hi;
1
'hi' declared without an initial value
→
47 mp_size_t mn = m->size;
48 mp_size_t bn = m->B_size;
49 mp_size_t sn = mn - bn;
50 mp_size_t rn = 2*mn;
51 mp_size_t i;
52 unsigned shift;
53
54 assert (sn > 0)((sn > 0) ? (void) (0) : __assert_fail ("sn > 0", "ecc-mod.c"
, 54, __PRETTY_FUNCTION__));
55
56 /* FIXME: Could use mpn_addmul_2. */
57 /* Eliminate sn limbs at a time */
58 if (m->B[bn-1] < ((mp_limb_t) 1 << (GMP_NUMB_BITS(64 - 0) - 1)))
2
←
Taking false branch
→
59 {
60 /* Multiply sn + 1 limbs at a time, so we get a mn+1 limb
61 product. Then we can absorb the carry in the high limb */
62 while (rn > 2 * mn - bn)
63 {
64 rn -= sn;
65
66 for (i = 0; i <= sn; i++)
67 rp[rn+i-1] = mpn_addmul_1__gmpn_addmul_1 (rp + rn - mn - 1 + i, m->B, bn, rp[rn+i-1]);
68 rp[rn-1] = rp[rn+sn-1]
69 + mpn_add_n__gmpn_add_n (rp + rn - sn - 1, rp + rn - sn - 1, rp + rn - 1, sn);
70 }
71 goto final_limbs;
72 }
73 else
74 {
75 while (rn >= 2 * mn - bn)
3
←
Loop condition is false. Execution continues on line 88
→
76 {
77 rn -= sn;
78
79 for (i = 0; i < sn; i++)
80 rp[rn+i] = mpn_addmul_1__gmpn_addmul_1 (rp + rn - mn + i, m->B, bn, rp[rn+i]);
81
82 hi = mpn_add_n__gmpn_add_n (rp + rn - sn, rp + rn - sn, rp + rn, sn);
83 hi = cnd_add_n (hi, rp + rn - mn, m->B, mn)__gmpn_cnd_add_n ((hi), (rp + rn - mn), (rp + rn - mn), (m->
B), (mn));
84 assert (hi == 0)((hi == 0) ? (void) (0) : __assert_fail ("hi == 0", "ecc-mod.c"
, 84, __PRETTY_FUNCTION__));
85 }
86 }
87
88 if (rn > mn)
4
←
Taking false branch
→
89 {
90 final_limbs:
91 sn = rn - mn;
92
93 for (i = 0; i < sn; i++)
94 rp[mn+i] = mpn_addmul_1__gmpn_addmul_1 (rp + i, m->B, bn, rp[mn+i]);
95
96 hi = mpn_add_n__gmpn_add_n (rp + bn, rp + bn, rp + mn, sn);
97 hi = sec_add_1_nettle_sec_add_1 (rp + bn + sn, rp + bn + sn, mn - bn - sn, hi);
98 }
99
100 shift = m->size * GMP_NUMB_BITS(64 - 0) - m->bit_size;
101 if (shift > 0)
5
←
Assuming 'shift' is > 0
→
6
←
Taking true branch
→
102 {
103 /* Combine hi with top bits, add in */
104 hi = (hi << shift) | (rp[mn-1] >> (GMP_NUMB_BITS(64 - 0) - shift));
7
←
The left operand of '<<' is a garbage value
105 rp[mn-1] = (rp[mn-1] & (((mp_limb_t) 1 << (GMP_NUMB_BITS(64 - 0) - shift)) - 1))
106 + mpn_addmul_1__gmpn_addmul_1 (rp, m->B_shifted, mn-1, hi);
107 }
108 else
109 {
110 hi = cnd_add_n (hi, rp, m->B_shifted, mn)__gmpn_cnd_add_n ((hi), (rp), (rp), (m->B_shifted), (mn));
111 assert (hi == 0)((hi == 0) ? (void) (0) : __assert_fail ("hi == 0", "ecc-mod.c"
, 111, __PRETTY_FUNCTION__));
112 }
113}