From bbe6b4650ad9522886e2292acc1c800b39a4def6 Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Thu, 8 Jul 2021 16:08:02 +0200
Subject: [PATCH] Futex: check for lower-half addrs manually.

---
 rmm                  |  2 +-
 src/syscall/futex.rs | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/rmm b/rmm
index b75c329..6bc59e7 160000
--- a/rmm
+++ b/rmm
@@ -1 +1 @@
-Subproject commit b75c329a273d194e313bc36a1ceab5362fd5f8e2
+Subproject commit 6bc59e70131135984a41216c45e4dc3a6395a30a
diff --git a/src/syscall/futex.rs b/src/syscall/futex.rs
index a130e12..2600b2e 100644
--- a/src/syscall/futex.rs
+++ b/src/syscall/futex.rs
@@ -48,7 +48,13 @@ pub fn futex(addr: usize, op: usize, val: usize, val2: usize, addr2: usize) -> R
         let active_table = ActivePageTable::new(TableKind::User);
         let virtual_address = VirtualAddress::new(addr);
 
-        if !crate::CurrentRmmArch::virt_is_valid(virtual_address) || crate::CurrentRmmArch::virt_kind(virtual_address) == TableKind::Kernel {
+        if !crate::CurrentRmmArch::virt_is_valid(virtual_address) {
+            return Err(Error::new(EFAULT));
+        }
+        // TODO: Use this all over the code, making sure that no user pointers that are higher half
+        // can get to the page table walking procedure.
+        #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+        if virtual_address.data() & (1 << 63) == (1 << 63) {
             return Err(Error::new(EFAULT));
         }
 
@@ -159,7 +165,13 @@ pub fn futex(addr: usize, op: usize, val: usize, val2: usize, addr2: usize) -> R
             let addr2_physaddr = unsafe {
                 let addr2_virt = VirtualAddress::new(addr2);
 
-                if !crate::CurrentRmmArch::virt_is_valid(addr2_virt) || crate::CurrentRmmArch::virt_kind(addr2_virt) == TableKind::Kernel {
+                if !crate::CurrentRmmArch::virt_is_valid(addr2_virt) {
+                    return Err(Error::new(EFAULT));
+                }
+
+                // TODO
+                #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+                if addr2_virt.data() & (1 << 63) == (1 << 63) {
                     return Err(Error::new(EFAULT));
                 }