diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index eee87ea..f5b3402 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -23,9 +23,11 @@ kernel-macros = { path = "macros" }
 cortex-a = { version = "6.x.x" }
 
 [features]
+default = ["aggressive_syscall"]
 pl011 = []
 pl031 = []
 verbose = []
+aggressive_syscall = []
 
 mach_qemu = ["pl011", "pl031"]
 mach_orangepi3 = []
diff --git a/kernel/src/syscall/arg.rs b/kernel/src/syscall/arg.rs
index 72a377d..caedd58 100644
--- a/kernel/src/syscall/arg.rs
+++ b/kernel/src/syscall/arg.rs
@@ -4,6 +4,24 @@ use crate::mem;
 use core::mem::size_of;
 use libsys::error::Errno;
 
+// TODO _mut() versions checking whether pages are actually writable
+
+macro_rules! invalid_memory {
+    ($($args:tt)+) => {
+        warnln!($($args)+);
+        #[cfg(feature = "aggressive_syscall")]
+        {
+            use libsys::signal::Signal;
+            use crate::proc::Thread;
+
+            let thread = Thread::current();
+            let proc = thread.owner().unwrap();
+            proc.enter_fault_signal(thread, Signal::SegmentationFault);
+        }
+        return Err(Errno::InvalidArgument);
+    }
+}
+
 fn translate(virt: usize) -> Option<usize> {
     let mut res: usize;
     unsafe {
@@ -33,23 +51,21 @@ pub fn validate_user_ptr_struct_option<'a, T>(base: usize) -> Result<Option<&'a
 /// Unwraps an user buffer reference
 pub fn validate_user_ptr<'a>(base: usize, len: usize) -> Result<&'a mut [u8], Errno> {
     if base > mem::KERNEL_OFFSET || base + len > mem::KERNEL_OFFSET {
-        warnln!(
+        invalid_memory!(
             "User region refers to kernel memory: base={:#x}, len={:#x}",
             base,
             len
         );
-        return Err(Errno::InvalidArgument);
     }
 
     for i in (base / mem::PAGE_SIZE)..((base + len + mem::PAGE_SIZE - 1) / mem::PAGE_SIZE) {
         if translate(i * mem::PAGE_SIZE).is_none() {
-            warnln!(
+            invalid_memory!(
                 "User region refers to unmapped memory: base={:#x}, len={:#x} (page {:#x})",
                 base,
                 len,
                 i * mem::PAGE_SIZE
             );
-            return Err(Errno::InvalidArgument);
         }
     }
 
@@ -77,49 +93,3 @@ pub fn validate_user_str<'a>(base: usize, len: usize) -> Result<&'a str, Errno>
         Errno::InvalidArgument
     })
 }
-//     if base > mem::KERNEL_OFFSET {
-//         warnln!("User string refers to kernel memory: base={:#x}", base);
-//         return Err(Errno::InvalidArgument);
-//     }
-//
-//     let base_ptr = base as *const u8;
-//     let mut len = 0;
-//     let mut page_valid = false;
-//     loop {
-//         if len == limit {
-//             warnln!("User string exceeded limit: base={:#x}", base);
-//             return Err(Errno::InvalidArgument);
-//         }
-//
-//         if (base + len) % mem::PAGE_SIZE == 0 {
-//             page_valid = false;
-//         }
-//
-//         if !page_valid && translate((base + len) & !0xFFF).is_none() {
-//             warnln!(
-//                 "User string refers to unmapped memory: base={:#x}, off={:#x}",
-//                 base,
-//                 len
-//             );
-//             return Err(Errno::InvalidArgument);
-//         }
-//
-//         page_valid = true;
-//
-//         let byte = unsafe { *base_ptr.add(len) };
-//         if byte == 0 {
-//             break;
-//         }
-//
-//         len += 1;
-//     }
-//
-//     let slice = unsafe { core::slice::from_raw_parts(base_ptr, len) };
-//     core::str::from_utf8(slice).map_err(|_| {
-//         warnln!(
-//             "User string contains invalid UTF-8 characters: base={:#x}",
-//             base
-//         );
-//         Errno::InvalidArgument
-//     })
-// }