Apple clang complaining of unknown 'dynamic_lookup'

[Atlante45]

afl-clang-fast++ gives the following error on macos when building a LLVMFuzzerTestOneInput harness with -fsanitize=fuzzer

clang++: error: no such file or directory: 'dynamic_lookup'

Steps to reproduce the behavior:

1. Compile the following file:

#include <cstdint>
#include <cstddef>

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
{
    return 0;
}

2. Using the following command:

afl-clang-fast++ -o fuzz main.cpp -fsanitize=fuzzer

Expected behavior
The compiler should not fail

Screen output/Screenshots

> afl-clang-fast++ --version
afl-cc++4.21a by Michal Zalewski, Laszlo Szekeres, Marc Heuse - mode: LLVM-PCGUARD
Homebrew clang version 18.1.5
Target: arm64-apple-darwin23.5.0
Thread model: posix
InstalledDir: /opt/homebrew/Cellar/llvm/18.1.5/bin

> clang++ --version
Apple clang version 15.0.0 (clang-1500.0.40.1)
Target: arm64-apple-darwin23.5.0
Thread model: posix
InstalledDir: /Applications/Xcode-15.0.0.15A240d.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

> cat main.cpp
#include <cstdint>
#include <cstddef>

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
{
    return 0;
}

> afl-clang-fast++ -o fuzz main.cpp -fsanitize=fuzzer
afl-cc++4.21a by Michal Zalewski, Laszlo Szekeres, Marc Heuse - mode: LLVM-PCGUARD
[+] Found '-fsanitize=fuzzer', replacing with libAFLDriver.a
clang++: error: no such file or directory: 'dynamic_lookup'

Additional context
I dug into the issue a bit myself and was able to fix it by applying this small patch before building AFL++:

diff --git a/src/afl-cc.c b/src/afl-cc.c
index 15a5bd8e..7fdb1fba 100644
--- a/src/afl-cc.c
+++ b/src/afl-cc.c
@@ -2360,8 +2360,7 @@ static void add_aflpplib(aflcc_state_t *aflcc) {
     insert_param(aflcc, afllib);

 #ifdef __APPLE__
-    insert_param(aflcc, "-Wl,-undefined");
-    insert_param(aflcc, "dynamic_lookup");
+    insert_param(aflcc, "-Wl,-undefined,dynamic_lookup");
 #endif

   }

I'm happy to submit a PR for it if you'd like but I'm not sure which versions of clang might be affected and if this can be applied to all of them indiscriminately.

With the patch:

> afl-clang-fast++ -o fuzz main.cpp -fsanitize=fuzzer
afl-cc++4.21a by Michal Zalewski, Laszlo Szekeres, Marc Heuse - mode: LLVM-PCGUARD
[+] Found '-fsanitize=fuzzer', replacing with libAFLDriver.a
SanitizerCoveragePCGUARD++4.21a
[+] Instrumented 1 locations with no collisions (non-hardened mode) of which are 0 handled and 0 unhandled selects.

[vanhauser-thc]

Ah thanks. Send a pr if you want to - this way you are visible as a contributor :)

[Atlante45]

That sounds good, thanks!
I'll put one up in the morning