[lsan] Fix leaks detected by sanitier

There were some leaks detected when running the test suite. But for `bcc_elf_get_buildid` which did not free the elf object, the rest of the leaks were isolated in the tests themselves which did not free some resources here and there.

This diff clears those leaks. This will allow running the tests suite in the future with LSAN enabled, helping in catching possible future leaks earlier.

Ran the sanitizer using:
```
docker run --privileged \
                   --pid=host \
                   -v $(pwd):/bcc \
                   -v /sys/kernel/debug:/sys/kernel/debug:rw \
                   -v /lib/modules:/lib/modules:ro \
                   -v /usr/src:/usr/src:ro \
                   -v /usr/include/linux:/usr/include/linux:ro \
                   bcc-docker \
                   /bin/bash -c \
                   'mkdir -p /bcc/build && cd /bcc/build && \
                    cmake -DCMAKE_BUILD_TYPE=Debug -DENABLE_LLVM_NATIVECODEGEN=OFF -DCMAKE_SANITIZE_TYPE=leak .. && make -j9'
```

followed by tests.

Before:

```
docker run -ti \
                    --privileged \
                    --network=host \
                    --pid=host \
                    -v $(pwd):/bcc \
                    -v /sys/kernel/debug:/sys/kernel/debug:rw \
                    -v /lib/modules:/lib/modules:ro \
                    -v /usr/src:/usr/src:ro \
                    -e CTEST_OUTPUT_ON_FAILURE=1 \
                    bcc-docker \
                    /bin/bash -c \
                    '/bcc/build/tests/wrapper.sh \
                        c_test_all sudo /bcc/build/tests/cc/test_libbcc' > /tmp/out
grep 'Indirect leak' /tmp/out | wc -l
99
grep 'Direct leak' /tmp/out | wc -l
4
```

Full out file available in https://gist.github.com/chantra/caa3c6f6a274895d8743fe9e48a7c528

After:
```
docker run -ti \
                    --privileged \
                    --network=host \
                    --pid=host \
                    -v $(pwd):/bcc \
                    -v /sys/kernel/debug:/sys/kernel/debug:rw \
                    -v /lib/modules:/lib/modules:ro \
                    -v /usr/src:/usr/src:ro \
                    -e CTEST_OUTPUT_ON_FAILURE=1 \
                    bcc-docker \
                    /bin/bash -c \
                    '/bcc/build/tests/wrapper.sh \
                        c_test_all sudo /bcc/build/tests/cc/test_libbcc'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test_libbcc is a Catch v1.4.0 host application.
Run with -? for options

-------------------------------------------------------------------------------
searching for modules in /proc/[pid]/maps
-------------------------------------------------------------------------------
/bcc/tests/cc/test_c_api.cc:497
...............................................................................

/bcc/tests/cc/test_c_api.cc:499: FAILED:
  REQUIRE( dummy_maps != __null )
with expansion:
  NULL != 0

-------------------------------------------------------------------------------
test bpf table
-------------------------------------------------------------------------------
/bcc/tests/cc/test_bpf_table.cc:24
...............................................................................

/bcc/tests/cc/test_bpf_table.cc:24: FAILED:
  {Unknown expression after the reported line}
due to unexpected exception with message:
  bad_function_call

-------------------------------------------------------------------------------
test bpf percpu tables
-------------------------------------------------------------------------------
/bcc/tests/cc/test_bpf_table.cc:94
...............................................................................

/bcc/tests/cc/test_bpf_table.cc:94: FAILED:
  {Unknown expression after the reported line}
due to unexpected exception with message:
  bad_function_call

-------------------------------------------------------------------------------
test bpf stack_id table
-------------------------------------------------------------------------------
/bcc/tests/cc/test_bpf_table.cc:227
...............................................................................

/bcc/tests/cc/test_bpf_table.cc:268: FAILED:
  REQUIRE( addrs.size() > 0 )
with expansion:
  0 > 0

Parse error:
    4@i%ra+1r
-------^
===============================================================================
test cases:  51 |  47 passed | 1 failed | 3 failed as expected
assertions: 984 | 980 passed | 1 failed | 3 failed as expected

Failed
```

src/cc/bcc_elf.c

@@ -1040,14 +1040,19 @@ int bcc_elf_get_buildid(const char *path, char *buildid)
 {
  Elf *e;
  int fd;
+ int rc = -1;
 
  if (openelf(path, &e, &fd) < 0)
  return -1;
 
  if (!find_buildid(e, buildid))
- return -1;
+ goto exit;
 
- return 0;
+ rc = 0;
+exit:
+ elf_end(e);
+ close(fd);
+ return rc;
 }
 
 int bcc_elf_symbol_str(const char *path, size_t section_idx,

tests/cc/test_bpf_table.cc

@@ -26,13 +26,13 @@ TEST_CASE("test bpf table", ebpf::bpf_module_rw_engine_enabled() ? "[bpf_table]"
  BPF_TABLE("hash", int, int, myhash, 128);
  )";
 
- ebpf::BPF *bpf(new ebpf::BPF);
+ ebpf::BPF bpf;
  ebpf::StatusTuple res(0);
  std::vector<std::pair<std::string, std::string>> elements;
- res = bpf->init(BPF_PROGRAM);
+ res = bpf.init(BPF_PROGRAM);
  REQUIRE(res.ok());
 
- ebpf::BPFTable t = bpf->get_table("myhash");
+ ebpf::BPFTable t = bpf.get_table("myhash");
 
  // update element
  std::string value;
@@ -78,8 +78,7 @@ TEST_CASE("test bpf table", ebpf::bpf_module_rw_engine_enabled() ? "[bpf_table]"
  REQUIRE(res.ok());
  REQUIRE(elements.size() == 0);
 
- // delete bpf_module, call to key/leaf printf/scanf must fail
- delete bpf;
+
 
  res = t.update_value("0x07", "0x42");
  REQUIRE(!res.ok());

tests/cc/test_c_api.cc

@@ -309,7 +309,11 @@ TEST_CASE("resolve symbol addresses for a given PID", "[c_api]") {
  REQUIRE(bcc_symcache_resolve_name(lazy_resolver, "/tmp/libz.so.1", "zlibVersion",
  &lazy_addr) == 0);
  REQUIRE(lazy_addr == addr);
+ bcc_free_symcache(resolver, child);
+ bcc_free_symcache(lazy_resolver, child);
  }
+ bcc_free_symcache(resolver, getpid());
+ bcc_free_symcache(lazy_resolver, getpid());
 }
 
 #define STACK_SIZE (1024 * 1024)
@@ -412,6 +416,8 @@ TEST_CASE("resolve symbols using /tmp/perf-pid.map", "[c_api]") {
  REQUIRE(sym.module);
  REQUIRE(string(sym.module) == perf_map_path(child));
  REQUIRE(string("right_next_door_fn") == sym.name);
+ bcc_free_symcache(resolver, child);
+
  }
 
  SECTION("separate namespace") {
@@ -428,6 +434,7 @@ TEST_CASE("resolve symbols using /tmp/perf-pid.map", "[c_api]") {
  REQUIRE(string(sym.module) == perf_map_path(1));
  REQUIRE(string("dummy_fn") == sym.name);
  unlink("/tmp/perf-1.map");
+ bcc_free_symcache(resolver, child);
  }
 
  SECTION("separate pid and mount namespace") {
@@ -444,6 +451,7 @@ TEST_CASE("resolve symbols using /tmp/perf-pid.map", "[c_api]") {
  // child is PID 1 in its namespace
  REQUIRE(string(sym.module) == perf_map_path(1));
  REQUIRE(string("dummy_fn") == sym.name);
+ bcc_free_symcache(resolver, child);
  }
 
  SECTION("separate pid and mount namespace, perf-map in host") {
@@ -465,6 +473,7 @@ TEST_CASE("resolve symbols using /tmp/perf-pid.map", "[c_api]") {
  REQUIRE(string("dummy_fn") == sym.name);
 
  unlink(path.c_str());
+ bcc_free_symcache(resolver, child);
  }
 
 
@@ -598,6 +607,7 @@ TEST_CASE("resolve global addr in libc in this process", "[c_api][!mayfail]") {
  res = bcc_resolve_global_addr(pid, sopath, local_addr, 0, &global_addr);
  REQUIRE(res == 0);
  REQUIRE(global_addr == (search.start + local_addr - search.file_offset));
+ free(sopath);
 }
 
 /* Consider the following scenario: we have some process that maps in a shared library [1] with a

tests/cc/test_usdt_probes.cc

@@ -404,6 +404,7 @@ TEST_CASE("test probing running Ruby process in namespaces",
  std::string module = pid_root + "usr/local/bin/ruby";
  REQUIRE(bcc_resolve_symname(module.c_str(), "rb_gc_mark", 0x0, ruby_pid, nullptr, &sym) == 0);
  REQUIRE(std::string(sym.module).find(pid_root, 1) == std::string::npos);
+ bcc_procutils_free(sym.module);
  }
 }