From 94fb1e44a7c2a5c98067761dc6f42057c3c76def Mon Sep 17 00:00:00 2001
From: Ben Kochie <superq@gmail.com>
Date: Thu, 26 Sep 2024 00:00:04 +0200
Subject: [PATCH] Fix: Add safety check to hwmon read

Avoid panic for accessing slice out of range in hwmon.

Fixes: https://github.com/prometheus/node_exporter/issues/3108

Signed-off-by: Ben Kochie <superq@gmail.com>
---
 collector/hwmon_linux.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/collector/hwmon_linux.go b/collector/hwmon_linux.go
index 3d53995c8d..9c0e065c3f 100644
--- a/collector/hwmon_linux.go
+++ b/collector/hwmon_linux.go
@@ -18,6 +18,7 @@ package collector
 
 import (
 	"errors"
+	"fmt"
 	"log/slog"
 	"os"
 	"path/filepath"
@@ -107,6 +108,9 @@ func sysReadFile(file string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	if n < 0 {
+		return nil, fmt.Errorf("failed to read file: %q, read returned negative bytes value: %d", file, n)
+	}
 
 	return b[:n], nil
 }