From 52c429c20701834eed2da8a2771e86bbcb2d86aa Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Sat, 12 Apr 2025 13:52:42 +0200
Subject: [PATCH 1/2] Add a couple of PROT_READ

Even though they are only used for writing, it is still UB to create a
mutable reference to memory that can't be read.
---
 redox-rt/src/proc.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/redox-rt/src/proc.rs b/redox-rt/src/proc.rs
index 81fad4f262..c04897fb3a 100644
--- a/redox-rt/src/proc.rs
+++ b/redox-rt/src/proc.rs
@@ -277,7 +277,7 @@ where
         {
             page
         } else if let Some(ref mut stack_page) = stack_page {
-            stack_page.remap(new_page_no * PAGE_SIZE, PROT_WRITE)?;
+            stack_page.remap(new_page_no * PAGE_SIZE, PROT_READ | PROT_WRITE)?;
             stack_page
         } else {
             let new = MmapGuard::map(
@@ -285,7 +285,7 @@ where
                 &Map {
                     offset: new_page_no * PAGE_SIZE,
                     size: PAGE_SIZE,
-                    flags: PROT_WRITE,
+                    flags: PROT_READ | PROT_WRITE,
                     address: 0, // let kernel decide
                 },
             )?;
@@ -658,7 +658,7 @@ impl MmapGuard {
                 size,
                 offset,
                 address: 0,
-                flags: PROT_WRITE,
+                flags: PROT_READ | PROT_WRITE,
             },
         )?;
         let slice = &mut *this.as_mut_ptr_slice();

From 4d82cd90f8919ad620b3dde793566b4ada281b2f Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Sat, 12 Apr 2025 13:54:09 +0200
Subject: [PATCH 2/2] Add a workaround for UB on arm64

---
 redox-rt/src/proc.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/redox-rt/src/proc.rs b/redox-rt/src/proc.rs
index c04897fb3a..26b730b861 100644
--- a/redox-rt/src/proc.rs
+++ b/redox-rt/src/proc.rs
@@ -647,6 +647,10 @@ impl MmapGuard {
 
         Ok(())
     }
+
+    // Without this inline(never), UB somewhere causes the flags to be set to 0 on arm64.
+    // FIXME Find the UB and fix it
+    #[inline(never)]
     pub unsafe fn map_mut_anywhere<'a>(
         fd: usize,
         offset: usize,