From 737a11389ccd741b581f35ff79e3ec159eb09764 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <bgianf@serenityos.org>
Date: Wed, 29 Dec 2021 02:54:25 -0800
Subject: [PATCH] Kernel: Fix info leak from `sockaddr_un` in socket syscalls

In `sys$accept4()` and `get_sock_or_peer_name()` we were not
initializing the padding of the `sockaddr_un` struct, leading to
an kernel information leak if the
caller looked back at it's contents.

Before Fix:

    37.766 Clipboard(11:11): accept4 Bytes:
    2f746d702f706f7274616c2f636c6970626f61726440eac130e7fbc1e8abbfc
    19c10ffc18440eac15485bcc130e7fbc1549feaca6c9deaca549feaca1bb0bc
    03efdf62c0e056eac1b402d7acd010ffc14602000001b0bc030100000050bf0
    5c24602000001e7fbc1b402d7ac6bdc

After Fix:

    0.603 Clipboard(11:11): accept4 Bytes:
    2f746d702f706f7274616c2f636c6970626f617264000000000000000000000
    000000000000000000000000000000000000000000000000000000000000000
    000000000000000000000000000000000000000000000000000000000000000
    0000000000000000000000000000000
---
 Kernel/Syscalls/socket.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Kernel/Syscalls/socket.cpp b/Kernel/Syscalls/socket.cpp
index b7cd325d53..16cc1580c0 100644
--- a/Kernel/Syscalls/socket.cpp
+++ b/Kernel/Syscalls/socket.cpp
@@ -108,7 +108,7 @@ ErrorOr<FlatPtr> Process::sys$accept4(Userspace<const Syscall::SC_accept4_params
     VERIFY(accepted_socket);
 
     if (user_address) {
-        sockaddr_un address_buffer;
+        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);
         TRY(copy_to_user(user_address, &address_buffer, address_size));
@@ -266,7 +266,7 @@ ErrorOr<void> Process::get_sock_or_peer_name(const Params& params)
     auto& socket = *description->socket();
     REQUIRE_PROMISE_FOR_SOCKET_DOMAIN(socket.domain());
 
-    sockaddr_un address_buffer;
+    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);