From a2c52caca24584b732c4e5c13dce78df9f0241d1 Mon Sep 17 00:00:00 2001
From: Rangi <sylvie.oukaour+rangi42@gmail.com>
Date: Sat, 22 Aug 2026 19:08:47 -0400
Subject: [PATCH] Disallow NUL characters in section names and assertion
 messages

Allowing these in object files would lose anything after the '\0'
when RGBLINK reads the object.
---
 src/asm/output.cpp            | 4 ++++
 src/asm/section.cpp           | 4 ++++
 test/asm/assert-nul.asm       | 1 +
 test/asm/assert-nul.err       | 2 ++
 test/asm/section-name-nul.asm | 2 ++
 test/asm/section-name-nul.err | 2 ++
 test/link/script.asm          | 2 +-
 7 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 test/asm/assert-nul.asm
 create mode 100644 test/asm/assert-nul.err
 create mode 100644 test/asm/section-name-nul.asm
 create mode 100644 test/asm/section-name-nul.err

diff --git a/src/asm/output.cpp b/src/asm/output.cpp
index 5d017888..2c22cd09 100644
--- a/src/asm/output.cpp
+++ b/src/asm/output.cpp
@@ -162,6 +162,10 @@ void out_CreatePatch(uint32_t type, Expression const &expr, uint32_t ofs, uint32
 void out_CreateAssert(
     AssertionType type, Expression const &expr, std::string const &message, uint32_t ofs
 ) {
+	if (message.find('\0') != std::string::npos) {
+		fatal("Assertion messages cannot contain '\\0' characters");
+	}
+
 	Assertion &assertion = assertions.emplace_front();
 
 	initPatch(assertion.patch, type, expr, ofs);
diff --git a/src/asm/section.cpp b/src/asm/section.cpp
index c9723f58..ea35ae39 100644
--- a/src/asm/section.cpp
+++ b/src/asm/section.cpp
@@ -544,6 +544,10 @@ void sect_NewSection(
     SectionSpec const &attrs,
     SectionModifier mod
 ) {
+	if (name.find('\0') != std::string::npos) {
+		fatal("Section names cannot contain '\\0' characters");
+	}
+
 	for (SectionStackEntry &entry : sectionStack) {
 		if (entry.section && entry.section->name == name) {
 			fatal("Section \"%s\" is already on the stack", name.c_str());
diff --git a/test/asm/assert-nul.asm b/test/asm/assert-nul.asm
new file mode 100644
index 00000000..3be84803
--- /dev/null
+++ b/test/asm/assert-nul.asm
@@ -0,0 +1 @@
+assert x, "oops \0 null"
diff --git a/test/asm/assert-nul.err b/test/asm/assert-nul.err
new file mode 100644
index 00000000..1c6d2b87
--- /dev/null
+++ b/test/asm/assert-nul.err
@@ -0,0 +1,2 @@
+FATAL: Assertion messages cannot contain '\0' characters
+    at assert-nul.asm(1)
diff --git a/test/asm/section-name-nul.asm b/test/asm/section-name-nul.asm
new file mode 100644
index 00000000..e888cbcf
--- /dev/null
+++ b/test/asm/section-name-nul.asm
@@ -0,0 +1,2 @@
+SECTION "test\0 foo", ROM0
+SECTION "test\0 bar", ROM0
diff --git a/test/asm/section-name-nul.err b/test/asm/section-name-nul.err
new file mode 100644
index 00000000..99fb73a4
--- /dev/null
+++ b/test/asm/section-name-nul.err
@@ -0,0 +1,2 @@
+FATAL: Section names cannot contain '\0' characters
+    at section-name-nul.asm(1)
diff --git a/test/link/script.asm b/test/link/script.asm
index 44f175c9..a173a9d9 100644
--- a/test/link/script.asm
+++ b/test/link/script.asm
@@ -7,4 +7,4 @@ SECTION "ROM2 1K", ROMX,BANK[2]
 	ds $1000
 SECTION "ROM2 1", ROMX,BANK[2]
 	ds 1
-SECTION "\\\"\'\n\r\t\0", ROM0
+SECTION "\\\"\'\n\r\t", ROM0