From a64d2bfbe67ce0520cdd9bb72ac8b9194269927a Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Sat, 9 Jul 2022 10:47:23 +0900
Subject: [PATCH] bigint.c (mpz_mul,mpz_mdiv): return early on zero.

---
 mrbgems/mruby-bigint/core/bigint.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mrbgems/mruby-bigint/core/bigint.c b/mrbgems/mruby-bigint/core/bigint.c
index d51efdf6f..b7892ef21 100644
--- a/mrbgems/mruby-bigint/core/bigint.c
+++ b/mrbgems/mruby-bigint/core/bigint.c
@@ -294,6 +294,10 @@ mpz_mul(mrb_state *mrb, mpz_t *ww, mpz_t *u, mpz_t *v)
   mp_limb cc;
   mpz_t w;
 
+  if (uzero(u) || uzero(v)) {
+    mpz_set_int(mrb, ww, 0);
+    return;
+  }
   mpz_init(mrb, &w);
   mpz_realloc(mrb, &w, (size_t)(u->sz + v->sz));
   for (j=0; j < 2*u->sz; j++) {
@@ -517,6 +521,10 @@ mpz_mdiv(mrb_state *mrb, mpz_t *q, mpz_t *x, mpz_t *y)
 {
   mpz_t r;
   short sn1 = x->sn, sn2 = y->sn, qsign;
+  if (uzero(x)) {
+    mpz_init_set_int(mrb, q, 0);
+    return;
+  }
   mpz_init(mrb,&r);
   udiv(mrb,q,&r,x,y);
   qsign = q->sn = sn1*sn2;