crypto/srp/srp_lib.c:202: error: BUFFER_OVERRUN_L3
  Offset added: [8, +oo] Size: [0, 67108856] by call to `BN_mod_exp`.
Showing all 34 steps of the trace


crypto/srp/srp_lib.c:174:1: Parameter `N->top`
172.   }
173.   
174. > BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
175.                               const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)
176.   {

crypto/srp/srp_lib.c:189:10: Call
187.           goto err;
188.   
189.       if (!BN_mod_exp(tmp, g, x, N, bn_ctx))
                ^
190.           goto err;
191.       if ((k = srp_Calc_k(N, g)) == NULL)

crypto/bn/bn_exp.c:89:1: Parameter `m->top`
  87.   }
  88.   
  89. > int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
  90.                  BN_CTX *ctx)
  91.   {

crypto/bn/bn_exp.c:134:9: Call
  132.   
  133.   #ifdef MONT_MUL_MOD
  134.       if (BN_is_odd(m)) {
                 ^
  135.   # ifdef MONT_EXP_WORD
  136.           if (a->top == 1 && !a->neg

crypto/bn/bn_lib.c:867:1: Parameter `a->top`
    865.   }
    866.   
    867. > int BN_is_odd(const BIGNUM *a)
    868.   {
    869.       return (a->top > 0) && (a->d[0] & 1);

crypto/bn/bn_exp.c:141:19: Call
  139.               && (BN_get_flags(m, BN_FLG_CONSTTIME) == 0)) {
  140.               BN_ULONG A = a->d[0];
  141.               ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL);
                           ^
  142.           } else
  143.   # endif

crypto/bn/bn_exp.c:1127:1: Parameter `m->top`
    1125.   }
    1126.   
    1127. > int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
    1128.                            const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
    1129.   {

crypto/srp/srp_lib.c:191:14: Call
189.       if (!BN_mod_exp(tmp, g, x, N, bn_ctx))
190.           goto err;
191.       if ((k = srp_Calc_k(N, g)) == NULL)
                    ^
192.           goto err;
193.       if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))

crypto/srp/srp_lib.c:45:1: Parameter `N->top`
  43.   }
  44.   
  45. > static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g)
  46.   {
  47.       /* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */

crypto/srp/srp_lib.c:48:12: Call
  46.   {
  47.       /* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
  48.       return srp_Calc_xy(N, g, N);
                   ^
  49.   }
  50.   

crypto/srp/srp_lib.c:23:1: Parameter `N->top`
    21.   /* calculate = SHA1(PAD(x) || PAD(y)) */
    22.   
    23. > static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)
    24.   {
    25.       unsigned char digest[SHA_DIGEST_LENGTH];

crypto/srp/srp_lib.c:27:16: Call
    25.       unsigned char digest[SHA_DIGEST_LENGTH];
    26.       unsigned char *tmp = NULL;
    27.       int numN = BN_num_bytes(N);
                         ^
    28.       BIGNUM *res = NULL;
    29.       if (x != N && BN_ucmp(x, N) >= 0)

crypto/bn/bn_lib.c:140:9: Call
      138.       bn_check_top(a);
      139.   
      140.       if (BN_is_zero(a))
                     ^
      141.           return 0;
      142.       return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));

crypto/bn/bn_lib.c:852:1: Parameter `a->top`
        850.   }
        851.   
        852. > int BN_is_zero(const BIGNUM *a)
        853.   {
        854.       return a->top == 0;

crypto/srp/srp_lib.c:193:10: Call
191.       if ((k = srp_Calc_k(N, g)) == NULL)
192.           goto err;
193.       if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
                ^
194.           goto err;
195.       if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))

crypto/bn/bn_mod.c:128:1: Parameter `m->top`
  126.   
  127.   /* slow but works */
  128. > int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
  129.                  BN_CTX *ctx)
  130.   {

crypto/srp/srp_lib.c:195:10: Call
193.       if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
194.           goto err;
195.       if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
                ^
196.           goto err;
197.       if (!BN_mul(tmp3, u, x, bn_ctx))

crypto/bn/bn_mod.c:105:1: Parameter `m->top`
  103.   }
  104.   
  105. > int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
  106.                  BN_CTX *ctx)
  107.   {

crypto/srp/srp_lib.c:202:23: Call
200.           goto err;
201.       K = BN_new();
202.       if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
                             ^
203.           BN_free(K);
204.           K = NULL;

crypto/bn/bn_exp.c:89:1: Parameter `m->top`
  87.   }
  88.   
  89. > int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
  90.                  BN_CTX *ctx)
  91.   {

crypto/bn/bn_exp.c:134:9: Call
  132.   
  133.   #ifdef MONT_MUL_MOD
  134.       if (BN_is_odd(m)) {
                 ^
  135.   # ifdef MONT_EXP_WORD
  136.           if (a->top == 1 && !a->neg

crypto/bn/bn_lib.c:867:1: Parameter `a->top`
    865.   }
    866.   
    867. > int BN_is_odd(const BIGNUM *a)
    868.   {
    869.       return (a->top > 0) && (a->d[0] & 1);

crypto/bn/bn_exp.c:149:15: Call
  147.   #ifdef RECP_MUL_MOD
  148.       {
  149.           ret = BN_mod_exp_recp(r, a, p, m, ctx);
                       ^
  150.       }
  151.   #else

crypto/bn/bn_exp.c:161:1: Parameter `m->top`
    159.   }
    160.   
    161. > int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
    162.                       const BIGNUM *m, BN_CTX *ctx)
    163.   {

crypto/bn/bn_exp.c:206:13: Call
    204.               goto err;
    205.       } else {
    206.           if (BN_RECP_CTX_set(&recp, m, ctx) <= 0)
                       ^
    207.               goto err;
    208.       }

crypto/bn/bn_recp.c:45:1: Parameter `d->top`
      43.   }
      44.   
      45. > int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
      46.   {
      47.       if (!BN_copy(&(recp->N), d))

crypto/bn/bn_recp.c:47:10: Call
      45.   int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
      46.   {
      47.       if (!BN_copy(&(recp->N), d))
                     ^
      48.           return 0;
      49.       BN_zero(&(recp->Nr));

crypto/bn/bn_lib.c:281:1: <Offset trace>
279.   }
280.   
281. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
282.   {
283.       bn_check_top(b);

crypto/bn/bn_lib.c:281:1: Parameter `b->top`
        279.   }
        280.   
        281. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
        282.   {
        283.       bn_check_top(b);

crypto/bn/bn_lib.c:281:1: <Length trace>
279.   }
280.   
281. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
282.   {
283.       bn_check_top(b);

crypto/bn/bn_lib.c:281:1: Parameter `*a->d`
        279.   }
        280.   
        281. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
        282.   {
        283.       bn_check_top(b);

crypto/bn/bn_lib.c:287:9: Call
        285.       if (a == b)
        286.           return a;
        287.       if (bn_wexpand(a, b->top) == NULL)
                       ^
        288.           return NULL;
        289.   

crypto/bn/bn_lib.c:948:1: Parameter `*a->d`
          946.   }
          947.   
          948. > BIGNUM *bn_wexpand(BIGNUM *a, int words)
          949.   {
          950.       return (words <= a->dmax) ? a : bn_expand2(a, words);

crypto/bn/bn_lib.c:291:9: Array access: Offset added: [8, +oo] Size: [0, 67108856] by call to `BN_mod_exp` 
        289.   
        290.       if (b->top > 0)
        291.           memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
                       ^
        292.   
        293.       a->neg = b->neg;

BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
{
    bn_check_top(b);
    if (a == b)
        return a;
    if (bn_wexpand(a, b->top) == NULL)
        return NULL;
    if (b->top > 0)
        memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
    a->neg = b->neg;
    a->top = b->top;
    a->flags |= b->flags & BN_FLG_FIXED_TOP;
    bn_check_top(a);
    return a;
}
['BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,\n                            const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)\n{\n    BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;\n    BN_CTX *bn_ctx;\n    if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL\n        || a == NULL || (bn_ctx = BN_CTX_new()) == NULL)\n        return NULL;\n    if ((tmp = BN_new()) == NULL ||\n        (tmp2 = BN_new()) == NULL ||\n        (tmp3 = BN_new()) == NULL)\n        goto err;\n    if (!BN_mod_exp(tmp, g, x, N, bn_ctx))\n        goto err;\n    if ((k = srp_Calc_k(N, g)) == NULL)\n        goto err;\n    if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))\n        goto err;\n    if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))\n        goto err;\n    if (!BN_mul(tmp3, u, x, bn_ctx))\n        goto err;\n    if (!BN_add(tmp2, a, tmp3))\n        goto err;\n    K = BN_new();\n    if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {\n        BN_free(K);\n        K = NULL;\n    }\n err:\n    BN_CTX_free(bn_ctx);\n    BN_clear_free(tmp);\n    BN_clear_free(tmp2);\n    BN_clear_free(tmp3);\n    BN_free(k);\n    return K;\n}', 'int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,\n               BN_CTX *ctx)\n{\n    int ret;\n    bn_check_top(a);\n    bn_check_top(p);\n    bn_check_top(m);\n#define MONT_MUL_MOD\n#define MONT_EXP_WORD\n#define RECP_MUL_MOD\n#ifdef MONT_MUL_MOD\n    if (BN_is_odd(m)) {\n# ifdef MONT_EXP_WORD\n        if (a->top == 1 && !a->neg\n            && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0)\n            && (BN_get_flags(a, BN_FLG_CONSTTIME) == 0)\n            && (BN_get_flags(m, BN_FLG_CONSTTIME) == 0)) {\n            BN_ULONG A = a->d[0];\n            ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL);\n        } else\n# endif\n            ret = BN_mod_exp_mont(r, a, p, m, ctx, NULL);\n    } else\n#endif\n#ifdef RECP_MUL_MOD\n    {\n        ret = BN_mod_exp_recp(r, a, p, m, ctx);\n    }\n#else\n    {\n        ret = BN_mod_exp_simple(r, a, p, m, ctx);\n    }\n#endif\n    bn_check_top(r);\n    return ret;\n}', 'int BN_is_odd(const BIGNUM *a)\n{\n    return (a->top > 0) && (a->d[0] & 1);\n}', 'int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,\n                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)\n{\n    BN_MONT_CTX *mont = NULL;\n    int b, bits, ret = 0;\n    int r_is_one;\n    BN_ULONG w, next_w;\n    BIGNUM *r, *t;\n    BIGNUM *swap_tmp;\n#define BN_MOD_MUL_WORD(r, w, m) \\\n                (BN_mul_word(r, (w)) && \\\n                (   \\\n                        (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))\n#define BN_TO_MONTGOMERY_WORD(r, w, mont) \\\n                (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))\n    if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) {\n        BNerr(BN_F_BN_MOD_EXP_MONT_WORD, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);\n        return 0;\n    }\n    bn_check_top(p);\n    bn_check_top(m);\n    if (!BN_is_odd(m)) {\n        BNerr(BN_F_BN_MOD_EXP_MONT_WORD, BN_R_CALLED_WITH_EVEN_MODULUS);\n        return 0;\n    }\n    if (m->top == 1)\n        a %= m->d[0];\n    bits = BN_num_bits(p);\n    if (bits == 0) {\n        if (BN_abs_is_word(m, 1)) {\n            ret = 1;\n            BN_zero(rr);\n        } else {\n            ret = BN_one(rr);\n        }\n        return ret;\n    }\n    if (a == 0) {\n        BN_zero(rr);\n        ret = 1;\n        return ret;\n    }\n    BN_CTX_start(ctx);\n    r = BN_CTX_get(ctx);\n    t = BN_CTX_get(ctx);\n    if (t == NULL)\n        goto err;\n    if (in_mont != NULL)\n        mont = in_mont;\n    else {\n        if ((mont = BN_MONT_CTX_new()) == NULL)\n            goto err;\n        if (!BN_MONT_CTX_set(mont, m, ctx))\n            goto err;\n    }\n    r_is_one = 1;\n    w = a;\n    for (b = bits - 2; b >= 0; b--) {\n        next_w = w * w;\n        if ((next_w / w) != w) {\n            if (r_is_one) {\n                if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                    goto err;\n                r_is_one = 0;\n            } else {\n                if (!BN_MOD_MUL_WORD(r, w, m))\n                    goto err;\n            }\n            next_w = 1;\n        }\n        w = next_w;\n        if (!r_is_one) {\n            if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))\n                goto err;\n        }\n        if (BN_is_bit_set(p, b)) {\n            next_w = w * a;\n            if ((next_w / a) != w) {\n                if (r_is_one) {\n                    if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                        goto err;\n                    r_is_one = 0;\n                } else {\n                    if (!BN_MOD_MUL_WORD(r, w, m))\n                        goto err;\n                }\n                next_w = a;\n            }\n            w = next_w;\n        }\n    }\n    if (w != 1) {\n        if (r_is_one) {\n            if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                goto err;\n            r_is_one = 0;\n        } else {\n            if (!BN_MOD_MUL_WORD(r, w, m))\n                goto err;\n        }\n    }\n    if (r_is_one) {\n        if (!BN_one(rr))\n            goto err;\n    } else {\n        if (!BN_from_montgomery(rr, r, mont, ctx))\n            goto err;\n    }\n    ret = 1;\n err:\n    if (in_mont == NULL)\n        BN_MONT_CTX_free(mont);\n    BN_CTX_end(ctx);\n    bn_check_top(rr);\n    return ret;\n}', 'static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g)\n{\n    return srp_Calc_xy(N, g, N);\n}', 'static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)\n{\n    unsigned char digest[SHA_DIGEST_LENGTH];\n    unsigned char *tmp = NULL;\n    int numN = BN_num_bytes(N);\n    BIGNUM *res = NULL;\n    if (x != N && BN_ucmp(x, N) >= 0)\n        return NULL;\n    if (y != N && BN_ucmp(y, N) >= 0)\n        return NULL;\n    if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)\n        goto err;\n    if (BN_bn2binpad(x, tmp, numN) < 0\n        || BN_bn2binpad(y, tmp + numN, numN) < 0\n        || !EVP_Digest(tmp, numN * 2, digest, NULL, EVP_sha1(), NULL))\n        goto err;\n    res = BN_bin2bn(digest, sizeof(digest), NULL);\n err:\n    OPENSSL_free(tmp);\n    return res;\n}', 'int BN_num_bits(const BIGNUM *a)\n{\n    int i = a->top - 1;\n    bn_check_top(a);\n    if (BN_is_zero(a))\n        return 0;\n    return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));\n}', 'int BN_is_zero(const BIGNUM *a)\n{\n    return a->top == 0;\n}', 'int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,\n               BN_CTX *ctx)\n{\n    BIGNUM *t;\n    int ret = 0;\n    bn_check_top(a);\n    bn_check_top(b);\n    bn_check_top(m);\n    BN_CTX_start(ctx);\n    if ((t = BN_CTX_get(ctx)) == NULL)\n        goto err;\n    if (a == b) {\n        if (!BN_sqr(t, a, ctx))\n            goto err;\n    } else {\n        if (!BN_mul(t, a, b, ctx))\n            goto err;\n    }\n    if (!BN_nnmod(r, t, m, ctx))\n        goto err;\n    bn_check_top(r);\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    return ret;\n}', 'int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,\n               BN_CTX *ctx)\n{\n    if (!BN_sub(r, a, b))\n        return 0;\n    return BN_nnmod(r, r, m, ctx);\n}', 'int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,\n                    const BIGNUM *m, BN_CTX *ctx)\n{\n    int i, j, bits, ret = 0, wstart, wend, window, wvalue;\n    int start = 1;\n    BIGNUM *aa;\n    BIGNUM *val[TABLE_SIZE];\n    BN_RECP_CTX recp;\n    if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(a, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) {\n        BNerr(BN_F_BN_MOD_EXP_RECP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);\n        return 0;\n    }\n    bits = BN_num_bits(p);\n    if (bits == 0) {\n        if (BN_abs_is_word(m, 1)) {\n            ret = 1;\n            BN_zero(r);\n        } else {\n            ret = BN_one(r);\n        }\n        return ret;\n    }\n    BN_CTX_start(ctx);\n    aa = BN_CTX_get(ctx);\n    val[0] = BN_CTX_get(ctx);\n    if (val[0] == NULL)\n        goto err;\n    BN_RECP_CTX_init(&recp);\n    if (m->neg) {\n        if (!BN_copy(aa, m))\n            goto err;\n        aa->neg = 0;\n        if (BN_RECP_CTX_set(&recp, aa, ctx) <= 0)\n            goto err;\n    } else {\n        if (BN_RECP_CTX_set(&recp, m, ctx) <= 0)\n            goto err;\n    }\n    if (!BN_nnmod(val[0], a, m, ctx))\n        goto err;\n    if (BN_is_zero(val[0])) {\n        BN_zero(r);\n        ret = 1;\n        goto err;\n    }\n    window = BN_window_bits_for_exponent_size(bits);\n    if (window > 1) {\n        if (!BN_mod_mul_reciprocal(aa, val[0], val[0], &recp, ctx))\n            goto err;\n        j = 1 << (window - 1);\n        for (i = 1; i < j; i++) {\n            if (((val[i] = BN_CTX_get(ctx)) == NULL) ||\n                !BN_mod_mul_reciprocal(val[i], val[i - 1], aa, &recp, ctx))\n                goto err;\n        }\n    }\n    start = 1;\n    wvalue = 0;\n    wstart = bits - 1;\n    wend = 0;\n    if (!BN_one(r))\n        goto err;\n    for (;;) {\n        if (BN_is_bit_set(p, wstart) == 0) {\n            if (!start)\n                if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx))\n                    goto err;\n            if (wstart == 0)\n                break;\n            wstart--;\n            continue;\n        }\n        j = wstart;\n        wvalue = 1;\n        wend = 0;\n        for (i = 1; i < window; i++) {\n            if (wstart - i < 0)\n                break;\n            if (BN_is_bit_set(p, wstart - i)) {\n                wvalue <<= (i - wend);\n                wvalue |= 1;\n                wend = i;\n            }\n        }\n        j = wend + 1;\n        if (!start)\n            for (i = 0; i < j; i++) {\n                if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx))\n                    goto err;\n            }\n        if (!BN_mod_mul_reciprocal(r, r, val[wvalue >> 1], &recp, ctx))\n            goto err;\n        wstart -= wend + 1;\n        wvalue = 0;\n        start = 0;\n        if (wstart < 0)\n            break;\n    }\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    BN_RECP_CTX_free(&recp);\n    bn_check_top(r);\n    return ret;\n}', 'int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)\n{\n    if (!BN_copy(&(recp->N), d))\n        return 0;\n    BN_zero(&(recp->Nr));\n    recp->num_bits = BN_num_bits(d);\n    recp->shift = 0;\n    return 1;\n}', 'BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)\n{\n    bn_check_top(b);\n    if (a == b)\n        return a;\n    if (bn_wexpand(a, b->top) == NULL)\n        return NULL;\n    if (b->top > 0)\n        memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);\n    a->neg = b->neg;\n    a->top = b->top;\n    a->flags |= b->flags & BN_FLG_FIXED_TOP;\n    bn_check_top(a);\n    return a;\n}', 'BIGNUM *bn_wexpand(BIGNUM *a, int words)\n{\n    return (words <= a->dmax) ? a : bn_expand2(a, words);\n}']