From e37ff67da2d733f9276651817d9287ab032f591c Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Wed, 12 Oct 2022 19:22:08 +0200
Subject: [PATCH] Make exec return an error if the loaded executable would use
 more memory than is currently available

---
 kernel/src/sys/exec.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/src/sys/exec.cpp b/kernel/src/sys/exec.cpp
index 5c242fbb..8d561dea 100644
--- a/kernel/src/sys/exec.cpp
+++ b/kernel/src/sys/exec.cpp
@@ -4,6 +4,7 @@
 #include "errno.h"
 #include "interrupts/Interrupts.h"
 #include "memory/MemoryManager.h"
+#include "memory/PMM.h"
 #include "std/stdlib.h"
 #include "std/string.h"
 #include "sys/elf/ELFLoader.h"
@@ -32,7 +33,8 @@ void sys_exec(Context* context, const char* pathname)
         return;
     }
 
-    if (ELFLoader::check_elf_image(program) < 0)
+    long memusage;
+    if ((memusage = ELFLoader::check_elf_image(program)) < 0)
     {
         context->rax = -ENOEXEC;
         return;
@@ -45,6 +47,13 @@ void sys_exec(Context* context, const char* pathname)
         return;
     }
 
+    if (memusage > PMM::get_free())
+    {
+        MemoryManager::release_pages((void*)allocated_stack, TASK_PAGES_IN_STACK);
+        context->rax = -ENOMEM;
+        return;
+    }
+
     Interrupts::disable();
     ASSERT(!Interrupts::are_enabled()); // This part is pretty sensitive.