From b6779f3831c48eca2f0ec6edc85a77b16db56270 Mon Sep 17 00:00:00 2001
From: kudasai <47227786+kudasaixc@users.noreply.github.com>
Date: Fri, 3 Jul 2026 18:55:08 +0200
Subject: [PATCH] fix(ansi): u16 overflow on oversized CSI parameters

The CSI parameter accumulator multiplied and added with no overflow
protection. A sequence like ESC[99999m overflows the u16 parameter
and, since the Zig objects are built with -O ReleaseSafe, trips the
safety check and lands in the panic handler: the kernel silently
freezes. Use saturating arithmetic so oversized parameters clamp to
65535 instead of bringing the machine down.
---
 src/kernel/ainsi.zig | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/kernel/ainsi.zig b/src/kernel/ainsi.zig
index 81474ed..2c1f187 100644
--- a/src/kernel/ainsi.zig
+++ b/src/kernel/ainsi.zig
@@ -79,7 +79,9 @@ export fn ansi_process_char(c: u8) void {
             switch (c) {
                 '0'...'9' => {
                     const n = c - '0';
-                    val.params[val.param_index] = (val.params[val.param_index] * 10) + n;
+                    // saturate instead of overflowing: a u16 overflow would
+                    // trip the ReleaseSafe safety check and hang the kernel
+                    val.params[val.param_index] = val.params[val.param_index] *| 10 +| n;
                 },
                 'J' => {
                     switch (val.params[0]) {