From 6434bf4b659a619b767e2a90047d9904f2bd565f Mon Sep 17 00:00:00 2001
From: Jeroen van Rijn <Kelimion@users.noreply.github.com>
Date: Sat, 7 Mar 2026 12:38:04 +0100
Subject: [PATCH] Limit maximum exponent in parsing of float/integer literals

---
 core/c/libc/math.odin |  2 +-
 src/big_int.cpp       | 22 ++++++++++++++++++++--
 src/parser.cpp        |  7 ++++++-
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/core/c/libc/math.odin b/core/c/libc/math.odin
index d0a015c70..434b67817 100644
--- a/core/c/libc/math.odin
+++ b/core/c/libc/math.odin
@@ -159,7 +159,7 @@ float_t          :: float
 double_t         :: double
 
 NAN              := transmute(double)(_nan_bit_pattern)
-INFINITY         :: 1e5000
+INFINITY         :: 0h7ff00000_00000000 // +Inf
 
 HUGE_VALF        :: INFINITY
 HUGE_VAL         :: double(INFINITY)
diff --git a/src/big_int.cpp b/src/big_int.cpp
index 0b0a9a400..7067a7c3d 100644
--- a/src/big_int.cpp
+++ b/src/big_int.cpp
@@ -197,8 +197,13 @@ gb_internal void big_int_from_string(BigInt *dst, String const &s, bool *success
 
 	BigInt b = {};
 	big_int_from_u64(&b, base);
+	defer (big_int_dealloc(&b));
+
 	mp_zero(dst);
 
+	BigInt digit = {};
+	defer (big_int_dealloc(&digit));
+
 	isize i = 0;
 	for (; i < len; i++) {
 		Rune r = cast(Rune)text[i];
@@ -224,9 +229,10 @@ gb_internal void big_int_from_string(BigInt *dst, String const &s, bool *success
 			}
 			break;
 		}
-		BigInt val = big_int_make_u64(v);
+
+		big_int_from_u64(&digit, v);
 		big_int_mul_eq(dst, &b);
-		big_int_add_eq(dst, &val);
+		big_int_add_eq(dst, &digit);
 	}
 	if (i < len && (text[i] == 'e' || text[i] == 'E')) {
 		i += 1;
@@ -235,6 +241,7 @@ gb_internal void big_int_from_string(BigInt *dst, String const &s, bool *success
 		if (text[i] == '+') {
 			i += 1;
 		}
+
 		u64 exp = 0;
 		for (; i < len; i++) {
 			char r = cast(char)text[i];
@@ -251,8 +258,19 @@ gb_internal void big_int_from_string(BigInt *dst, String const &s, bool *success
 			exp *= 10;
 			exp += v;
 		}
+
+		// NOTE(Jeroen): A valid integer can never have an exponent larger than 308 (per `max(f64)`).
+		//               As an integer, not even larger than `max(u128)` which has a base 10 exponent of 38.
+		//               But we also use this path to parse float literals like those in `core:math.pow10_f64`,
+		//               so we have to stick with 1e308.
+		if (exp > 308) {
+			*success = false;
+			return;
+		}
+
 		BigInt tmp = {};
 		mp_init(&tmp);
+		defer (big_int_dealloc(&tmp));
 		big_int_exp_u64(&tmp, &b, exp, success);
 		big_int_mul_eq(dst, &tmp);
 	}
diff --git a/src/parser.cpp b/src/parser.cpp
index 84fbc5130..ca81159b4 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -804,7 +804,12 @@ gb_internal ExactValue exact_value_from_token(AstFile *f, Token const &token) {
 			syntax_error(token, "Invalid integer literal");
 			break;
 		case Token_Float:
-			syntax_error(token, "Invalid float literal");
+			// NOTE(Jeroen): Could be an integer, see `exact_value_float_from_string`
+			if (!string_contains_char(s, '.') && !string_contains_char(s, '-')) {
+				syntax_error(token, "Invalid integer literal");
+			} else {
+				syntax_error(token, "Invalid float literal");
+			}
 			break;
 		default:
 			syntax_error(token, "Invalid token literal");