From 575c7ed41428bf08b7b6419284f45ee29da502ed Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 16 Feb 2021 11:32:00 +0100
Subject: [PATCH] Kernel: Make sys$msyscall() EFAULT on non-user address

Fixes #5361.
---
 Kernel/Syscalls/mmap.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Kernel/Syscalls/mmap.cpp b/Kernel/Syscalls/mmap.cpp
index 6f6c04e459..8eeee8be33 100644
--- a/Kernel/Syscalls/mmap.cpp
+++ b/Kernel/Syscalls/mmap.cpp
@@ -563,6 +563,9 @@ int Process::sys$msyscall(void* address)
         return 0;
     }
 
+    if (!is_user_address(VirtualAddress { address }))
+        return -EFAULT;
+
     auto* region = space().find_region_containing(Range { VirtualAddress { address }, 1 });
     if (!region)
         return -EINVAL;