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mruby-bigint: fix memory leak in mpz_mul_all_ones

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Add MRB_TRY/MRB_CATCH to ensure local mpz_t variables are freed when
an exception (e.g., RangeError from shift overflow) occurs during
the all-ones multiplication optimization.

Co-authored-by: Claude <noreply@anthropic.com>
This commit is contained in:
Yukihiro "Matz" Matsumoto
2026-01-12 17:57:22 +09:00
parent 9471b132c4
commit 26a1064d99
1 changed files with 46 additions and 33 deletions
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mrbgems/mruby-bigint/core/bigint.c
+46 -33
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@@ -1460,50 +1460,63 @@ mpz_mul_sparse(mpz_ctx_t *ctx, mpz_t *w, mpz_t *sparse, mpz_t *dense)
static void
mpz_mul_all_ones(mpz_ctx_t *ctx, mpz_t *w, size_t n, size_t m)
{
mpz_t a;
struct mrb_jmpbuf *prev_jmp = ctx->mrb->jmp;
struct mrb_jmpbuf c_jmp;
mpz_t a = {0, 0, 0};
mpz_t b = {0, 0, 0};
if (n == m) {
/* Squaring: (2^n - 1)^2 = 2^(2n) - 2^(n+1) + 1 */
/* Start with 2^(2n) */
mpz_init(ctx, &a);
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, w, &a, 2*n);
MRB_TRY(&c_jmp) {
ctx->mrb->jmp = &c_jmp;
/* Subtract 2^(n+1) */
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, &a, &a, n+1);
mpz_sub(ctx, w, w, &a);
if (n == m) {
/* Squaring: (2^n - 1)^2 = 2^(2n) - 2^(n+1) + 1 */
/* Start with 2^(2n) */
mpz_init(ctx, &a);
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, w, &a, 2*n);
/* Add 1 */
mpz_add_int(ctx, w, 1);
mpz_clear(ctx, &a);
}
else {
/* General: (2^n - 1) * (2^m - 1) = 2^(n+m) - 2^n - 2^m + 1 */
mpz_t b;
mpz_init(ctx, &a);
mpz_init(ctx, &b);
/* Subtract 2^(n+1) */
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, &a, &a, n+1);
mpz_sub(ctx, w, w, &a);
/* Start with 2^(n+m) */
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, w, &a, n+m);
/* Add 1 */
mpz_add_int(ctx, w, 1);
}
else {
/* General: (2^n - 1) * (2^m - 1) = 2^(n+m) - 2^n - 2^m + 1 */
mpz_init(ctx, &a);
mpz_init(ctx, &b);
/* Subtract 2^n */
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, &a, &a, n);
mpz_sub(ctx, w, w, &a);
/* Start with 2^(n+m) */
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, w, &a, n+m);
/* Subtract 2^m */
mpz_set_int(ctx, &b, 1);
mpz_mul_2exp(ctx, &b, &b, m);
mpz_sub(ctx, w, w, &b);
/* Subtract 2^n */
mpz_set_int(ctx, &a, 1);
mpz_mul_2exp(ctx, &a, &a, n);
mpz_sub(ctx, w, w, &a);
/* Add 1 */
mpz_add_int(ctx, w, 1);
/* Subtract 2^m */
mpz_set_int(ctx, &b, 1);
mpz_mul_2exp(ctx, &b, &b, m);
mpz_sub(ctx, w, w, &b);
/* Add 1 */
mpz_add_int(ctx, w, 1);
}
ctx->mrb->jmp = prev_jmp;
mpz_clear(ctx, &a);
mpz_clear(ctx, &b);
}
MRB_CATCH(&c_jmp) {
ctx->mrb->jmp = prev_jmp;
mpz_clear(ctx, &a);
mpz_clear(ctx, &b);
MRB_THROW(ctx->mrb->jmp);
}
MRB_END_EXC(&c_jmp);
}
/* w = u^2 (squaring - faster than general multiplication) */