From df5ea97c51e63f84ce30e8db9d8617b035e2ac38 Mon Sep 17 00:00:00 2001
From: Itamar <itamar8910@gmail.com>
Date: Sat, 2 Jan 2021 12:03:28 +0200
Subject: [PATCH] Kernel: Release scheduler_lock in ptrace once we know tracee
 is stopped

This fixes a kernel crash that occured when calling ptrace with PT_PEEK
on non paged-in memory.
The crash occurred because we were holding the scheduler lock while
trying to read from the disk's block device, which we do not allow.
Fixes #4740
---
 Kernel/Ptrace.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Kernel/Ptrace.cpp b/Kernel/Ptrace.cpp
index 552c9656dd..90b65e0370 100644
--- a/Kernel/Ptrace.cpp
+++ b/Kernel/Ptrace.cpp
@@ -86,6 +86,8 @@ KResultOr<u32> handle_syscall(const Kernel::Syscall::SC_ptrace_params& params, P
     if (peer->state() == Thread::State::Running)
         return KResult(-EBUSY);
 
+    scheduler_lock.unlock();
+
     switch (params.request) {
     case PT_CONTINUE:
         peer->send_signal(SIGCONT, &caller);