diff --git a/LarpixServer/Account/Utils.cs b/LarpixServer/Account/Utils.cs
index 568c514..f1b0188 100644
--- a/LarpixServer/Account/Utils.cs
+++ b/LarpixServer/Account/Utils.cs
@@ -28,8 +28,8 @@ public class Utils
         }
         
         int hash = id.GetHashCode();
-        if (hash < 0) hash = -hash; // Or use Math.Abs, but hash < 0 logic avoids OverflowException on int.MinValue
-        return _userLocksArray[hash % _userLocksArray.Length];
+        int index = (hash & 0x7FFFFFFF) % _userLocksArray.Length;
+        return _userLocksArray[index];
     }
 
     public static string GetIdFromUsernameWD(string usernameWD)
@@ -111,6 +111,10 @@ public class Utils
     
     public static async Task<string> IdFromName(string name)
     {
+        if (name == null || !IsValidUsername(name, out _))
+        {
+            return "0";
+        }
         string path = $"{ACCOUNTS_NAME_DIR}/{name.ToLowerInvariant()}";
         if (!Fs.Exists(path))
         {
@@ -288,6 +292,10 @@ public class Utils
 
     public static async Task<byte[]> GetUserPublicStorageEntry(string id, string entry)
     {
+        if (string.IsNullOrEmpty(entry) || entry.Contains("..") || entry.Contains("/") || entry.Contains("\\"))
+        {
+            return new byte[] {};
+        }
         string path = $"{ACCOUNTS_DATA_DIR}/{id}/storage/public/{entry}";
         if (!Fs.Exists(path))
         {
diff --git a/LarpixServer/Filesystem/Fs.cs b/LarpixServer/Filesystem/Fs.cs
index d1d3260..ab2a8d5 100644
--- a/LarpixServer/Filesystem/Fs.cs
+++ b/LarpixServer/Filesystem/Fs.cs
@@ -31,8 +31,8 @@ public class Fs
         }
         
         int hash = path.GetHashCode();
-        if (hash < 0) hash = -hash; // Or use Math.Abs, but hash < 0 logic avoids OverflowException on int.MinValue
-        return _fileLocksArray[hash % _fileLocksArray.Length];
+        int index = (hash & 0x7FFFFFFF) % _fileLocksArray.Length;
+        return _fileLocksArray[index];
     }
 
     public static void ProcessCacheSpace()
@@ -208,7 +208,10 @@ public class Fs
         sem1.Wait();
         try
         {
-            sem2.Wait();
+            if (!ReferenceEquals(sem1, sem2))
+            {
+                sem2.Wait();
+            }
             try
             {
                 File.Move(path, newPath);
@@ -220,7 +223,10 @@ public class Fs
             }
             finally
             {
-                sem2.Release();
+                if (!ReferenceEquals(sem1, sem2))
+                {
+                    sem2.Release();
+                }
             }
         }
         finally