Merge "libfstab_fuzzer: fuzz TransformFstabForDsu() and skip mount logic" (882c1681) · Commits · e / os / android_system_core

fs_mgr/fs_mgr_fstab.cpp

+14 −7

Original line number	Diff line number	Diff line
		@@ -754,10 +754,11 @@ bool ReadFstabFromDt(Fstab* fstab, bool verbose) {
		}

		#ifdef NO_SKIP_MOUNT
		bool SkipMountingPartitions(Fstab*, bool) {
		return true;
		}
		static constexpr bool kNoSkipMount = true;
		#else
		static constexpr bool kNoSkipMount = false;
		#endif

		// For GSI to skip mounting /product and /system_ext, until there are well-defined interfaces
		// between them and /system. Otherwise, the GSI flashed on /system might not be able to work with
		// device-specific /product and /system_ext. skip_mount.cfg belongs to system_ext partition because
		@@ -765,17 +766,24 @@ bool SkipMountingPartitions(Fstab*, bool) {
		// /system/system_ext because GSI is a single system.img that includes the contents of system_ext
		// partition and product partition under /system/system_ext and /system/product, respectively.
		bool SkipMountingPartitions(Fstab* fstab, bool verbose) {
		if (kNoSkipMount) {
		return true;
		}

		static constexpr char kSkipMountConfig[] = "/system/system_ext/etc/init/config/skip_mount.cfg";

		std::string skip_config;
		std::string skip_mount_config;
		auto save_errno = errno;
		if (!ReadFileToString(kSkipMountConfig, &skip_config)) {
		if (!ReadFileToString(kSkipMountConfig, &skip_mount_config)) {
		errno = save_errno; // missing file is expected
		return true;
		}
		return SkipMountWithConfig(skip_mount_config, fstab, verbose);
		}

		bool SkipMountWithConfig(const std::string& skip_mount_config, Fstab* fstab, bool verbose) {
		std::vector<std::string> skip_mount_patterns;
		for (const auto& line : Split(skip_config, "\n")) {
		for (const auto& line : Split(skip_mount_config, "\n")) {
		if (line.empty() \|\| StartsWith(line, "#")) {
		continue;
		}
		@@ -801,7 +809,6 @@ bool SkipMountingPartitions(Fstab* fstab, bool verbose) {
		fstab->erase(remove_from, fstab->end());
		return true;
		}
		#endif

		// Loads the fstab file and combines with fstab entries passed in from device tree.
		bool ReadDefaultFstab(Fstab* fstab) {

fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp

+16 −2

Original line number	Diff line number	Diff line
		@@ -14,13 +14,27 @@
		// limitations under the License.
		//

		#include <cstdio>
		#include <string>
		#include <vector>

		#include <fstab/fstab.h>
		#include <fuzzer/FuzzedDataProvider.h>

		extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
		std::string make_fstab_str(reinterpret_cast<const char*>(data), size);
		FuzzedDataProvider fdp(data, size);

		std::string make_fstab_str = fdp.ConsumeRandomLengthString();
		std::string dsu_slot = fdp.ConsumeRandomLengthString(30);
		std::vector<std::string> dsu_partitions = {
		fdp.ConsumeRandomLengthString(30),
		fdp.ConsumeRandomLengthString(30),
		};
		std::string skip_mount_config = fdp.ConsumeRemainingBytesAsString();

		android::fs_mgr::Fstab fstab;
		android::fs_mgr::ParseFstabFromString(make_fstab_str, /* proc_mounts = */ false, &fstab);
		android::fs_mgr::TransformFstabForDsu(&fstab, dsu_slot, dsu_partitions);
		android::fs_mgr::SkipMountWithConfig(skip_mount_config, &fstab, /* verbose = */ false);

		return 0;
		}

fs_mgr/include_fstab/fstab/fstab.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -97,6 +97,8 @@ using Fstab = std::vector<FstabEntry>;
		bool ParseFstabFromString(const std::string& fstab_str, bool proc_mounts, Fstab* fstab_out);
		// Exported for testability. Regular users should use ReadDefaultFstab().
		std::string GetFstabPath();
		// Exported for testability.
		bool SkipMountWithConfig(const std::string& skip_config, Fstab* fstab, bool verbose);

		bool ReadFstabFromFile(const std::string& path, Fstab* fstab);
		bool ReadFstabFromDt(Fstab* fstab, bool verbose = true);