From c6e23e45c587cfd771ccafbb8359a9cfbde27f70 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Przemys=C5=82aw=20R=2E=20Kusiak?= <spaemann@protonmail.com>
Date: Sat, 18 Sep 2021 04:07:19 +0200
Subject: [PATCH] Kernel: Let MouseDevice and KeyboardDevice write method
 return EINVAL

Currently, writing anything to `/dev/mouse0` or `/dev/keyboard0` causes
the Kernel to panic. The reason for this is that
`[Mouse,Keyboard]Device::write` always returns 0, which is explicitly
prohibited by `VERIFY` macro in `Process::sys$write`.  The fix seems
trivial; `write` should return EINVAL instead (as is the case with, for
example, `KCOVDevice`).
---
 Kernel/Devices/HID/KeyboardDevice.cpp | 5 -----
 Kernel/Devices/HID/KeyboardDevice.h   | 2 +-
 Kernel/Devices/HID/MouseDevice.cpp    | 5 -----
 Kernel/Devices/HID/MouseDevice.h      | 2 +-
 4 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/Kernel/Devices/HID/KeyboardDevice.cpp b/Kernel/Devices/HID/KeyboardDevice.cpp
index 68a5efedc2e..fd59ffe8253 100644
--- a/Kernel/Devices/HID/KeyboardDevice.cpp
+++ b/Kernel/Devices/HID/KeyboardDevice.cpp
@@ -306,11 +306,6 @@ KResultOr<size_t> KeyboardDevice::read(OpenFileDescription&, u64, UserOrKernelBu
     return nread;
 }
 
-KResultOr<size_t> KeyboardDevice::write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t)
-{
-    return 0;
-}
-
 KResult KeyboardDevice::ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg)
 {
     switch (request) {
diff --git a/Kernel/Devices/HID/KeyboardDevice.h b/Kernel/Devices/HID/KeyboardDevice.h
index 05353fe3455..b6f80ddf4b9 100644
--- a/Kernel/Devices/HID/KeyboardDevice.h
+++ b/Kernel/Devices/HID/KeyboardDevice.h
@@ -27,7 +27,7 @@ public:
     // ^CharacterDevice
     virtual KResultOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
     virtual bool can_read(const OpenFileDescription&, size_t) const override;
-    virtual KResultOr<size_t> write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t) override;
+    virtual KResultOr<size_t> write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t) override { return EINVAL; }
     virtual bool can_write(const OpenFileDescription&, size_t) const override { return true; }
 
     // ^HIDDevice
diff --git a/Kernel/Devices/HID/MouseDevice.cpp b/Kernel/Devices/HID/MouseDevice.cpp
index a3c263d570f..152ded74212 100644
--- a/Kernel/Devices/HID/MouseDevice.cpp
+++ b/Kernel/Devices/HID/MouseDevice.cpp
@@ -48,9 +48,4 @@ KResultOr<size_t> MouseDevice::read(OpenFileDescription&, u64, UserOrKernelBuffe
     return nread;
 }
 
-KResultOr<size_t> MouseDevice::write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t)
-{
-    return 0;
-}
-
 }
diff --git a/Kernel/Devices/HID/MouseDevice.h b/Kernel/Devices/HID/MouseDevice.h
index 6df59de9d78..14029050fee 100644
--- a/Kernel/Devices/HID/MouseDevice.h
+++ b/Kernel/Devices/HID/MouseDevice.h
@@ -25,7 +25,7 @@ public:
     // ^CharacterDevice
     virtual KResultOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
     virtual bool can_read(const OpenFileDescription&, size_t) const override;
-    virtual KResultOr<size_t> write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t) override;
+    virtual KResultOr<size_t> write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t) override { return EINVAL; }
     virtual bool can_write(const OpenFileDescription&, size_t) const override { return true; }
 
     // ^HIDDevice