From eee38788c5b26d2b98afe43583d37f54ecd60113 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alexander=20Mei=C3=9Fner?= <AlexanderMeissner@gmx.net>
Date: Mon, 9 Dec 2024 17:48:23 +0100
Subject: [PATCH] Fix - Interpreter `check_pc!` (#643)

* Adds test_err_callx_oob_max.

* Removes unnecessary debug mode arithmetic guard.
---
 src/interpreter.rs |  6 +++++-
 tests/execution.rs | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/interpreter.rs b/src/interpreter.rs
index dcb38f5b..0a0edc95 100644
--- a/src/interpreter.rs
+++ b/src/interpreter.rs
@@ -67,7 +67,11 @@ macro_rules! check_pc {
     ($self:expr, $next_pc:ident, $target_pc:expr) => {
         if ($target_pc as usize)
             .checked_mul(ebpf::INSN_SIZE)
-            .and_then(|offset| $self.program.get(offset..offset + ebpf::INSN_SIZE))
+            .and_then(|offset| {
+                $self
+                    .program
+                    .get(offset..offset.saturating_add(ebpf::INSN_SIZE))
+            })
             .is_some()
         {
             $next_pc = $target_pc;
diff --git a/tests/execution.rs b/tests/execution.rs
index 0989119e..22439ffa 100644
--- a/tests/execution.rs
+++ b/tests/execution.rs
@@ -2490,6 +2490,20 @@ fn test_err_callx_oob_high() {
     );
 }
 
+#[test]
+fn test_err_callx_oob_max() {
+    test_interpreter_and_jit_asm!(
+        "
+        mov64 r0, -0x8
+        hor64 r0, -0x1
+        callx r0
+        exit",
+        [],
+        TestContextObject::new(3),
+        ProgramResult::Err(EbpfError::CallOutsideTextSegment),
+    );
+}
+
 #[test]
 fn test_callx_unaligned_text_section() {
     test_interpreter_and_jit_elf!(