From 51e7adcbee23ec05295a7709ad4cd2c070335752 Mon Sep 17 00:00:00 2001
From: Xphalnos <yiga.steam@gmail.com>
Date: Mon, 13 Oct 2025 21:05:43 +0200
Subject: [PATCH 1/2] Replace free() by munmap()

Signed-off-by: Xphalnos <yiga.steam@gmail.com>
---
 src/host/memory/arena.cpp | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/src/host/memory/arena.cpp b/src/host/memory/arena.cpp
index 7c1d8e2..89e8bc1 100644
--- a/src/host/memory/arena.cpp
+++ b/src/host/memory/arena.cpp
@@ -35,7 +35,6 @@ arena_t arena_init(size_t capacity)
     };
     return arena;
 }
-// new more memsafe code (ownedbywuigi) (i give up on windows compatibility for now, will stick to the old unsafe code)
 
 void* arena_allocate(memory::arena_t* arena, const std::size_t size)
 {
@@ -55,14 +54,24 @@ void arena_reset(memory::arena_t* arena)
 void arena_free(memory::arena_t* arena)
 {
     PVM_ASSERT(arena != nullptr);
+
+#ifdef WIN32
+    const int free = VirtualFree(arena->data, 0, MEM_RELEASE);
+
+    PVM_ASSERT(free != 0);
+
+    if (free == 0)
+        PVM_ASSERT_MSG(false, "Failed to free arena memory");
+#else
+    const int free = munmap(arena->data, arena->capacity);
+
+    PVM_ASSERT(free == 0);
+
+    if (free == -1)
+        PVM_ASSERT_MSG(false, "Failed to free arena memory");
+#endif
+
     arena->capacity = 0;
     arena->size = 0;
-
-    // TODO(GloriousTaco:memory): Replace free with a memory safe alternative.
-#ifdef WIN32
-    VirtualFree(arena->data, 0, MEM_RELEASE);
-#else
-    free(arena->data);
-#endif
 }
 }  // namespace pound::host::memory

From 194b15b55680860303800897329193c9612c8221 Mon Sep 17 00:00:00 2001
From: Ronald Caesar <github43132@proton.me>
Date: Fri, 17 Oct 2025 16:28:02 -0400
Subject: [PATCH 2/2] host: add assertions

Munmap can fail if the length argument is 0, and the address being freed
is not a multiple of the host's page size.

Signed-off-by: Ronald Caesar <github43132@proton.me>
---
 src/host/memory/arena.cpp | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/host/memory/arena.cpp b/src/host/memory/arena.cpp
index 89e8bc1..a0b74ec 100644
--- a/src/host/memory/arena.cpp
+++ b/src/host/memory/arena.cpp
@@ -5,6 +5,7 @@
 #ifdef WIN32
 #include <Windows.h>
 #else
+#include <unistd.h>
 #include <sys/mman.h>
 #endif
 
@@ -53,22 +54,26 @@ void arena_reset(memory::arena_t* arena)
 }
 void arena_free(memory::arena_t* arena)
 {
-    PVM_ASSERT(arena != nullptr);
+    PVM_ASSERT(nullptr != arena);
+    PVM_ASSERT(nullptr != arena->data);
 
 #ifdef WIN32
-    const int free = VirtualFree(arena->data, 0, MEM_RELEASE);
-
-    PVM_ASSERT(free != 0);
-
-    if (free == 0)
+    size_t size = 0;
+    const int return_val = VirtualFree(arena->data, size, MEM_RELEASE);
+    if (0 == return_val)
+    {
         PVM_ASSERT_MSG(false, "Failed to free arena memory");
+    }
 #else
-    const int free = munmap(arena->data, arena->capacity);
-
-    PVM_ASSERT(free == 0);
-
-    if (free == -1)
+    long page_size = sysconf(_SC_PAGESIZE);
+    PVM_ASSERT(page_size > 0);
+    PVM_ASSERT(arena->capacity > 0);
+    PVM_ASSERT(0 == ((uintptr_t)arena->data % (size_t)page_size));
+    int return_val = munmap(arena->data, arena->capacity);
+    if (-1 == return_val)
+    {
         PVM_ASSERT_MSG(false, "Failed to free arena memory");
+    }
 #endif
 
     arena->capacity = 0;