Fix cmplog for qemu fork executor (#3145)

* update cmplog map ptr

* do not lower it; it's still there so it should be working

Author: rmalmain

fuzzers/binary_only/fuzzbench_fork_qemu/Cargo.lock

@@ -30,7 +30,7 @@ test: build harness
 
     rm -rf out/
     timeout 15s {{ FUZZER }} {{ BUILD_DIR }}/harness -- --libafl-in ../../inprocess/libfuzzer_libpng/corpus --libafl-out out ./harness | tee fuzz_stdout.log
-    if grep -qa "corpus: 2" fuzz_stdout.log; then
+    if grep -qa "objectives: 1" fuzz_stdout.log; then
         echo "Fuzzer is working"
     else
         echo "Fuzzer does not generate any testcases or any crashes"

fuzzers/binary_only/fuzzbench_fork_qemu/Justfile

@@ -56,7 +56,7 @@ use libafl_qemu::{
     Emulator, GuestReg, MmapPerms, QemuExitError, QemuExitReason, QemuForkExecutor,
     QemuShutdownCause, Regs,
 };
-use libafl_targets::EDGES_MAP_DEFAULT_SIZE;
+use libafl_targets::{CMPLOG_MAP_PTR, EDGES_MAP_DEFAULT_SIZE};
 #[cfg(unix)]
 use nix::unistd::dup;
 
@@ -267,6 +267,9 @@ fn fuzz(
     let time_observer = TimeObserver::new("time");
 
     // Create an observation channel using cmplog map
+    unsafe {
+        CMPLOG_MAP_PTR = cmplog_map_ptr;
+    }
     let cmplog_observer = unsafe { CmpLogObserver::with_map_ptr("cmplog", cmplog_map_ptr, true) };
 
     let map_feedback = MaxMapFeedback::new(&edges_observer);