From 73ccda8b4be53435cc8acb14fc5ba22a571cd31a Mon Sep 17 00:00:00 2001
From: Alwin Berger <alwin.berger@tu-dortmund.de>
Date: Wed, 9 Nov 2022 13:35:56 +0100
Subject: [PATCH] libafl_qemu: fallback cpu for read-/write_mem

In systemmode, current_cpu may not be set.
In such cases use the first cpus memory access methods.
---
 libafl_qemu/src/emu.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libafl_qemu/src/emu.rs b/libafl_qemu/src/emu.rs
index 01389df9f3..c4fba77c7e 100644
--- a/libafl_qemu/src/emu.rs
+++ b/libafl_qemu/src/emu.rs
@@ -658,11 +658,15 @@ impl Emulator {
     }
 
     pub unsafe fn write_mem(&self, addr: GuestAddr, buf: &[u8]) {
-        self.current_cpu().unwrap().write_mem(addr, buf);
+        self.current_cpu()
+            .unwrap_or(self.cpu_from_index(0))
+            .write_mem(addr, buf);
     }
 
     pub unsafe fn read_mem(&self, addr: GuestAddr, buf: &mut [u8]) {
-        self.current_cpu().unwrap().read_mem(addr, buf);
+        self.current_cpu()
+            .unwrap_or(self.cpu_from_index(0))
+            .read_mem(addr, buf);
     }
 
     #[must_use]