Everywhere: Fix some alignment issues

When creating uninitialized storage for variables, we need to make sure
that the alignment is correct. Fixes a KUBSAN failure when running
kernels compiled with Clang.

In `Syscalls/socket.cpp`, we can simply use local variables, as
`sockaddr_un` is a POD type.

Along with moving the `alignas` specifier to the correct member,
`AK::Optional`'s internal buffer has been made non-zeroed by default.
GCC emitted bogus uninitialized memory access warnings, so we now use
`__builtin_launder` to tell the compiler that we know what we are doing.
This might disable some optimizations, but judging by how GCC failed to
notice that the memory's initialization is dependent on `m_has_value`,
I'm not sure that's a bad thing.

1 files changed, 7 insertions, 7 deletions

diff --git a/Kernel/Syscalls/socket.cpp b/Kernel/Syscalls/socket.cpp
index 108e3967f1..f6f15384e5 100644
--- a/Kernel/Syscalls/socket.cpp
+++ b/Kernel/Syscalls/socket.cpp
@@ -119,10 +119,10 @@ KResultOr<FlatPtr> Process::sys$accept4(Userspace<const Syscall::SC_accept4_para
     VERIFY(accepted_socket);
 
     if (user_address) {
-        u8 address_buffer[sizeof(sockaddr_un)];
+        sockaddr_un address_buffer;
         address_size = min(sizeof(sockaddr_un), static_cast<size_t>(address_size));
-        accepted_socket->get_peer_address((sockaddr*)address_buffer, &address_size);
-        if (!copy_to_user(user_address, address_buffer, address_size))
+        accepted_socket->get_peer_address((sockaddr*)&address_buffer, &address_size);
+        if (!copy_to_user(user_address, &address_buffer, address_size))
             return EFAULT;
         if (!copy_to_user(user_address_size, &address_size))
             return EFAULT;
@@ -311,13 +311,13 @@ int Process::get_sock_or_peer_name(const Params& params)
     auto& socket = *description->socket();
     REQUIRE_PROMISE_FOR_SOCKET_DOMAIN(socket.domain());
 
-    u8 address_buffer[sizeof(sockaddr_un)];
+    sockaddr_un address_buffer;
     addrlen_value = min(sizeof(sockaddr_un), static_cast<size_t>(addrlen_value));
     if constexpr (sockname)
-        socket.get_local_address((sockaddr*)address_buffer, &addrlen_value);
+        socket.get_local_address((sockaddr*)&address_buffer, &addrlen_value);
     else
-        socket.get_peer_address((sockaddr*)address_buffer, &addrlen_value);
-    if (!copy_to_user(params.addr, address_buffer, addrlen_value))
+        socket.get_peer_address((sockaddr*)&address_buffer, &addrlen_value);
+    if (!copy_to_user(params.addr, &address_buffer, addrlen_value))
         return EFAULT;
     if (!copy_to_user(params.addrlen, &addrlen_value))
         return EFAULT;