From f0768376e1639d12a328745ef69c90d584138074 Mon Sep 17 00:00:00 2001
From: Neil Horman <nhorman@openssl.org>
Date: Fri, 26 Jul 2024 11:01:05 -0400
Subject: [PATCH] limit bignums to 128 bytes

Keep us from spinning forever doing huge amounts of math in the fuzzer

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/25013)
---
 fuzz/bignum.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fuzz/bignum.c b/fuzz/bignum.c
index d7c3716aac..783e915977 100644
--- a/fuzz/bignum.c
+++ b/fuzz/bignum.c
@@ -52,11 +52,12 @@ int FuzzerTestOneInput(const uint8_t *buf, size_t len)
      */
     if (len > 2) {
         len -= 3;
-        l1 = (buf[0] * len) / 255;
+        /* limit l1, l2, and l3 to be no more than 512 bytes */
+        l1 = ((buf[0] * len) / 255) % 512;
         ++buf;
-        l2 = (buf[0] * (len - l1)) / 255;
+        l2 = ((buf[0] * (len - l1)) / 255) % 512;
         ++buf;
-        l3 = len - l1 - l2;
+        l3 = (len - l1 - l2) % 512;
 
         s1 = buf[0] & 1;
         s3 = buf[0] & 4;