From 4743afeaf466b7ae718a96ca71be46305c51a793 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <b.gianfo@gmail.com>
Date: Sun, 21 Feb 2021 08:03:03 -0800
Subject: [PATCH] Kernel: Use already computed nfds_checked value when copying
 from user mode.

- We've already computed the number of fds * sizeof(pollfd), so use it
  instead of needlessly doing it again.

- Use fds_copy.data() instead off address of indexing the vector.
---
 Kernel/Syscalls/select.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Kernel/Syscalls/select.cpp b/Kernel/Syscalls/select.cpp
index 8010e37248..6d464d1f58 100644
--- a/Kernel/Syscalls/select.cpp
+++ b/Kernel/Syscalls/select.cpp
@@ -169,7 +169,7 @@ int Process::sys$poll(Userspace<const Syscall::SC_poll_params*> user_params)
         if (nfds_checked.has_overflow())
             return -EFAULT;
         fds_copy.resize(params.nfds);
-        if (!copy_from_user(&fds_copy[0], &params.fds[0], params.nfds * sizeof(pollfd)))
+        if (!copy_from_user(fds_copy.data(), &params.fds[0], nfds_checked.value()))
             return -EFAULT;
     }
 
@@ -242,7 +242,7 @@ int Process::sys$poll(Userspace<const Syscall::SC_poll_params*> user_params)
             fds_with_revents++;
     }
 
-    if (params.nfds > 0 && !copy_to_user(&params.fds[0], &fds_copy[0], params.nfds * sizeof(pollfd)))
+    if (params.nfds > 0 && !copy_to_user(&params.fds[0], fds_copy.data(), params.nfds * sizeof(pollfd)))
         return -EFAULT;
 
     return fds_with_revents;