lkl · tavip · Feb 28, 2025 · Jan 19, 2025 · Jan 19, 2025 · Feb 26, 2025
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -37,11 +37,6 @@ jobs:
             runs_on: ubuntu-22.04
             shell: bash
             build_options: "LLVM=1 CROSS_COMPILE=x86_64-linux-gnu"
-          - displayTargetName: lkl-fuzzers
-            os: unix
-            runs_on: ubuntu-22.04
-            shell: bash
-            build_options: "LKL_FUZZING=1 fuzzers"
           - displayTargetName: zpoline
           # maybe integrate with default Linux build once the function becomes stable
             os: unix
@@ -178,3 +173,27 @@ jobs:
         run: sudo pip install ply GitPython
       - name: Check coding style
         run: tools/lkl/scripts/checkpatch.sh
+
+  fuzzers:
+    runs-on: ubuntu-22.04
+    name: fuzzers
+    env:
+      PROTOBUF_MUTATOR_DIR: /tmp/libprotobuf-mutator
+    steps:
+      - name: Checkout
+        with:
+          fetch-depth: 0
+        uses: actions/checkout@v4
+      - name: Install clang toolchain
+        run: |
+          sudo apt update -y
+          sudo apt install -y clang lld llvm
+      - name: Install libprotobuf-mutator prerequisites
+        run: |
+          sudo apt update -y
+          sudo apt install -y binutils cmake ninja-build liblzma-dev libz-dev \
+            pkg-config autoconf libtool
+      - name: Build libprotobuf-mutator
+        run: tools/lkl/scripts/libprotobuf-mutator-build.sh
+      - name: Build fuzzers
+        run: make -j4 -C tools/lkl LKL_FUZZING=1 MMU=1 fuzzers
diff --git a/arch/lkl/configs/fuzzing_defconfig b/arch/lkl/configs/fuzzing_defconfig
@@ -191,3 +191,5 @@ CONFIG_KASAN_STACK_ENABLE=y
 CONFIG_KASAN_GENERIC=y
 CONFIG_KASAN_OUTLINE=y
 CONFIG_FRAME_WARN=0
+
+CONFIG_DEVTMPFS=y
diff --git a/arch/lkl/scripts/headers_install.py b/arch/lkl/scripts/headers_install.py
@@ -132,6 +132,7 @@ def replace(h):
 
 find_headers("arch/lkl/include/uapi/asm/syscalls.h")
 headers.add("arch/lkl/include/uapi/asm/host_ops.h")
+find_headers("include/uapi/linux/android/binder.h")
 find_headers("include/uapi/linux/uhid.h")
 find_headers("include/uapi/linux/mman.h")
 find_headers("include/uapi/linux/input-event-codes.h")
@@ -181,7 +182,7 @@ def replace(h):
 p = re.compile(r"static\s+__always_inline(\s+\w+)+\s+(\w+)\([^)]*\)\s")
 find_symbols(p, defines)
 p = re.compile(r"enum\s+(\w*)\s*{([^}]*)}", re.M|re.S)
-q = re.compile(r"(\w+)\s*(,|=[^,]*|$)", re.M|re.S)
+q = re.compile(r"(\w+)\s*(,|=\s*\w+\s*\([^()]*\)|=[^,]*|$)", re.M|re.S)
 find_enums(p, q, defines)
 
 # needed for i386

diff --git a/tools/lkl/Makefile b/tools/lkl/Makefile
@@ -24,7 +24,7 @@ ifeq (,$(srctree))
 endif
 export srctree
 
--include ../scripts/Makefile.include
+include ../scripts/Makefile.include
 
 # OUTPUT fixup should be *after* include ../scripts/Makefile.include
 ifneq ($(OUTPUT),)
@@ -42,13 +42,13 @@ conf: $(OUTPUT)Makefile.conf
 $(OUTPUT)Makefile.conf $(OUTPUT)include/kernel_config.h $(OUTPUT)/kernel.config: Makefile.autoconf
 	$(call QUIET_AUTOCONF, headers)$(MAKE) -f Makefile.autoconf -s
 
--include $(OUTPUT)Makefile.conf
+include $(OUTPUT)Makefile.conf
 
 export CFLAGS += -I$(OUTPUT)/include -Iinclude -Wall -g -O2 -Wextra \
 	 -Wno-unused-parameter \
 	 -Wno-missing-field-initializers -fno-strict-aliasing
 
--include Targets
+include Targets
 
 # Expand targets to output location and suffix but preserve special
 # targets (e.g. .WAIT)
@@ -114,13 +114,58 @@ $(OUTPUT)%-in.o: $(OUTPUT)lib/lkl.o FORCE
 $(OUTPUT)cpfromfs$(EXESUF): cptofs$(EXESUF)
 	$(Q)if ! [ -e $@ ]; then ln -s $< $@; fi
 
+# START: fuzzing-related build-rules
+FUZZ_TARGETS := $(fuzzers-y:%=$(OUTPUT)%$(EXESUF))
+fuzzers: $(FUZZ_TARGETS)
+
+# Enable libFuzzer fuzzing instrumentation for the LKL fuzzers
+$(OUTPUT)fuzzers/%$(EXESUF): LDFLAGS += -fsanitize=fuzzer --coverage
+
+# Binder fuzzer is special: built with C++ toolchain and linked with libprotobuf-mutator
+$(OUTPUT)fuzzers/binder%$(EXESUF): $(OUTPUT)fuzzers/binder%-in.o $(OUTPUT)liblkl.a
+	$(QUIET_LINK)$(CXX) $(LDFLAGS) $(LDFLAGS_$*-y) -o $@ $^ $(LDLIBS) $(LDLIBS_$*-y)
+
+# Track all the protoc generated files for 'clean' target
+PROTOC_GENERATED_FILES :=
+
+read_proto_deps = \
+  $(strip $(shell grep PROTOBUF_MUTATOR_PROTO $(1) | sed 's/^.*= //g'))
+
+define gen_protobuf_deps =
+  $(eval FUZZER_SRC_DIR := $(dir $(srctree)/tools/lkl/$(1)))
+  $(eval FUZZER_PROTO_FILES := $(call read_proto_deps,$(FUZZER_SRC_DIR)Build))
+  $(eval FUZZER_PROTO_FILES := $(FUZZER_PROTO_FILES:.proto=.pb.cpp) \
+    $(FUZZER_PROTO_FILES:.proto=.pb.h))
+  $(eval FUZZER_PROTO_FILES := \
+    $(addprefix $(FUZZER_SRC_DIR),$(FUZZER_PROTO_FILES)))
+  PROTOC_GENERATED_FILES += $(FUZZER_PROTO_FILES)
+  $(OUTPUT)$(1)-in.o: $(FUZZER_PROTO_FILES)
+endef
+
+# Add generated .pb.cc and pb.h files for libprotobuf-mutator as prerequisites
+# for the corresponding fuzz targets to have them made using the rule below.
+$(foreach fuzzer,$(fuzzers-y),$(eval $(call gen_protobuf_deps,$(fuzzer))))
+
+# TODO: Cannot depend on the corresponding $(srctree)/tools/lkl/%.proto file
+# due to the pattern rule
+# '$(OUTPUT)%$(EXESUF): $(OUTPUT)%-in.o $(OUTPUT)liblkl.a' above. For POSIX
+# target $(EXESUF) is an empty string, thus, target $(OUTPUT)%$(EXESUF) would
+# match any source file and will try to make it.
+# Update once https://github.com/lkl/linux/issues/573 is fixed.
+$(srctree)/tools/lkl/%.pb.cpp $(srctree)/tools/lkl/%.pb.h&: FORCE
+	$(PROTOC_PATH) --cpp_out=$(@D) --proto_path=$(@D) $(@F:pb.cpp=proto)
+	mv $(@:.cpp=.cc) $@
+
+# END: fuzzing-related build-rules
+
 clean:
 	$(call QUIET_CLEAN, vmlinux)$(MAKE) -C ../.. ARCH=lkl $(KOPT) clean
 	$(call QUIET_CLEAN, objects)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd'\
 	 -delete -o -name '\.*.d' -delete
 	$(call QUIET_CLEAN, headers)$(RM) -r $(OUTPUT)/include/lkl/
 	$(call QUIET_CLEAN, liblkl.a)$(RM) $(OUTPUT)/liblkl.a
-	$(call QUIET_CLEAN, targets)$(RM) $(TARGETS) bin/stat
+	$(call QUIET_CLEAN, targets)$(RM) $(TARGETS) $(FUZZ_TARGETS) bin/stat
+	$(call QUIET_CLEAN, gen_protos)$(RM) $(PROTOC_GENERATED_FILES)
 
 mrproper: clean
 	$(call QUIET_CLEAN, vmlinux)$(MAKE) -C ../.. ARCH=lkl $(KOPT) mrproper
@@ -153,12 +198,6 @@ install: headers_install libraries_install programs_install
 run-tests:
 	./tests/run.py $(tests)
 
-# Enable libFuzzer fuzzing instrumentation for the LKL fuzzers
-$(OUTPUT)fuzzers/%$(EXESUF): LDFLAGS += -fsanitize=fuzzer --coverage
-
-FUZZ_TARGETS := $(fuzzers-y:%=$(OUTPUT)%$(EXESUF))
-fuzzers: $(FUZZ_TARGETS)
-
 FORCE: ;
 .PHONY: all clean clean-conf mrproper FORCE run-tests
 .PHONY: headers_install libraries_install programs_install install

diff --git a/tools/lkl/Makefile.autoconf b/tools/lkl/Makefile.autoconf
@@ -169,13 +169,89 @@ define do_autoconf_llvm
   $(eval LLVM_SUFFIX := $(if $(filter -%,$(LLVM)),$(LLVM)))
   export CLANG_TARGET_FLAGS_lkl := $(CROSS_COMPILE)
   export CC := $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
+  export CXX := $(LLVM_PREFIX)clang++$(LLVM_SUFFIX)
   export LD := $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
   export AR := $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
   $(eval LD := $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
   $(eval CC := $(LLVM_PREFIX)clang$(LLVM_SUFFIX))
   $(eval LD_FMT := $(call llvm_target_to_ld_fmt))
 endef
 
+define define_libprotobuf_mutator
+  $(eval PROTOC_PATH := $(PROTOBUF_MUTATOR_DIR)/build/external.protobuf/bin/protoc)
+  export PROTOC_PATH := $(PROTOC_PATH)
+
+  # Tell compiler where to find libprotobuf-mutator-related headers
+  export LIBPROTOBUF_MUTATOR_INCLUDES_DIR := -I$(PROTOBUF_MUTATOR_DIR) \
+    -I$(PROTOBUF_MUTATOR_DIR)/build/external.protobuf/include
+
+  # Tell linker where to find libprotobuf-mutator-related static libs
+  export LIBPROTOBUF_MUTATOR_LIBS_DIR := -L$(PROTOBUF_MUTATOR_DIR)/build/src \
+	  -L$(PROTOBUF_MUTATOR_DIR)/build/src/libfuzzer \
+	  -L$(PROTOBUF_MUTATOR_DIR)/build/external.protobuf/lib
+
+  # The same list of absl dependencies as in libprotobuf-mutator cmake config:
+  # https://github.com/google/libprotobuf-mutator/blob/master/cmake/external/protobuf.cmake
+  $(eval LIBPROTOBUF_LIBS := protobufd \
+    absl_bad_any_cast_impl absl_bad_optional_access absl_bad_variant_access \
+    absl_base absl_city absl_civil_time absl_cord absl_cord_internal \
+    absl_cordz_functions absl_cordz_handle absl_cordz_info \
+    absl_cordz_sample_token absl_crc_cord_state absl_crc_cpu_detect \
+    absl_crc_internal absl_crc32c absl_debugging_internal \
+    absl_demangle_internal absl_die_if_null absl_examine_stack \
+    absl_exponential_biased absl_failure_signal_handler \
+    absl_flags_commandlineflag absl_flags_commandlineflag_internal \
+    absl_flags_config absl_flags_internal absl_flags_marshalling \
+    absl_flags_parse absl_flags_private_handle_accessor \
+    absl_flags_program_name absl_flags_reflection absl_flags_usage \
+    absl_flags_usage_internal absl_graphcycles_internal absl_hash \
+    absl_hashtablez_sampler absl_int128 absl_kernel_timeout_internal \
+    absl_leak_check absl_log_entry absl_log_flags absl_log_globals \
+    absl_log_initialize absl_log_internal_check_op \
+    absl_log_internal_conditions absl_log_internal_format \
+    absl_log_internal_globals absl_log_internal_log_sink_set \
+    absl_log_internal_message absl_log_internal_nullguard \
+    absl_log_internal_proto absl_log_severity \
+    absl_log_sink absl_low_level_hash absl_malloc_internal \
+    absl_periodic_sampler absl_random_distributions \
+    absl_random_internal_distribution_test_util absl_random_internal_platform \
+    absl_random_internal_pool_urbg absl_random_internal_randen \
+    absl_random_internal_randen_hwaes absl_random_internal_randen_hwaes_impl \
+    absl_random_internal_randen_slow absl_random_internal_seed_material \
+    absl_random_seed_gen_exception absl_random_seed_sequences \
+    absl_raw_hash_set absl_raw_logging_internal absl_scoped_set_env \
+    absl_spinlock_wait absl_stacktrace absl_status \
+    absl_statusor absl_str_format_internal absl_strerror \
+    absl_string_view absl_strings absl_strings_internal \
+    absl_symbolize absl_synchronization absl_throw_delegate \
+    absl_time absl_time_zone utf8_validity)
+
+  export LIBPROTOBUF_MUTATOR_LIBS := \
+    -lprotobuf-mutator-libfuzzer -lprotobuf-mutator \
+    $(addprefix -l,$(LIBPROTOBUF_LIBS))
+
+  # Libprotobuf-mutator build safety checks
+  $(if $(wildcard $(PROTOC_PATH)),,\
+    $(error Cannot find protoc binary at $(PROTOC_PATH). \
+      Refer to documentation at tools/lkl/fuzzers/binder/README.md))
+
+  $(if $(wildcard $(PROTOBUF_MUTATOR_DIR)/build/src/libprotobuf-mutator.a),,\
+    $(error Cannot find libprotobuf-mutator.a in \
+      $(abspath $(PROTOBUF_MUTATOR_DIR)/build/src/). \
+      Refer to documentation at tools/lkl/fuzzers/binder/README.md))
+
+  $(if $(wildcard $(PROTOBUF_MUTATOR_DIR)/build/src/libfuzzer/libprotobuf-mutator-libfuzzer.a),,\
+    $(error Cannot find libprotobuf-mutator-libfuzzer.a in \
+      $(abspath $(PROTOBUF_MUTATOR_DIR)/build/src/libfuzzer/). \
+      Refer to documentation at tools/lkl/fuzzers/binder/README.md))
+
+  $(foreach protobuf_lib,$(LIBPROTOBUF_LIBS),\
+     $(if $(wildcard $(PROTOBUF_MUTATOR_DIR)/build/external.protobuf/lib/lib$(protobuf_lib).a),,\
+        $(error Cannot find lib$(protobuf_lib).a in \
+          $(PROTOBUF_MUTATOR_DIR)/build/external.protobuf/lib/. \
+          Refer to documentation at tools/lkl/fuzzers/binder/README.md)))
+endef
+
 define do_autoconf_fuzzing
   export KCONFIG := fuzzing_defconfig
   export LLVM := 1
@@ -185,6 +261,9 @@ define do_autoconf_fuzzing
   $(eval kasan := yes)
   $(call set_kernel_config,LKL_FUZZING,y)
   $(if $(LKL_LINE_COV),$(call set_kernel_config,LKL_LINE_COV,y))
+  $(if $(MMU),$(call set_kernel_config,ANDROID_BINDER_IPC,y))
+  $(if $(PROTOBUF_MUTATOR_DIR),$(call define_libprotobuf_mutator))
+  LDFLAGS += -fuse-ld=lld
 endef
 
 define mmu_test_enable

diff --git a/tools/lkl/Targets b/tools/lkl/Targets
@@ -42,4 +42,7 @@ endif
 
 # LKL fuzzers
 fuzzers-y += fuzzers/hid/hid-fuzzer
+fuzzers-$(LKL_HOST_CONFIG_MMU) += fuzzers/binder/binder-fuzzer
 
+LDFLAGS_/binder-fuzzer-$(LKL_HOST_CONFIG_MMU) += $(LIBPROTOBUF_MUTATOR_LIBS_DIR)
+LDLIBS_/binder-fuzzer-$(LKL_HOST_CONFIG_MMU) += $(LIBPROTOBUF_MUTATOR_LIBS)
diff --git a/tools/lkl/fuzzers/binder/Build b/tools/lkl/fuzzers/binder/Build
@@ -0,0 +1,8 @@
+CXXFLAGS += $(CFLAGS) $(LIBPROTOBUF_MUTATOR_INCLUDES_DIR)
+
+CXXFLAGS_binder.pb.o += -DNDEBUG
+
+PROTOBUF_MUTATOR_PROTO := binder.proto
+
+binder-fuzzer-y += binder-fuzzer.o binder.o binder.pb.o
+