RFR: 8266187: Memory leak in appendBootClassPath()

[Kevin Walls]

On Wed, 28 Apr 2021 06:38:57 GMT, Wang Huang <whuang at openjdk.org> wrote:

> Dear All, 
>     I find a memory leak in `appendBootClassPath()`
> https://github.com/openjdk/jdk/blob/75a2354dc276e107d64516d20fc72bc7ef3d5f86/src/java.instrument/share/native/libinstrument/InvocationAdapter.c#L950
> * we malloc `resolved` from resolve(parent, path)
> * we use `resolved` in line 951 
> * we don't free() this memory after using.
> 
> I think we can fix this bug by adding a free() after line 951 as my commit.
> Thank you for your review. Any suggestion is welcome.
> 
> Yours , 
> Wang Huang

Hi,
I didn't find it immediately obvious that this was safe, but I followed things and think that it is correct:

The malloc'd pointer gets passed to...
JvmtiEnv::AddToBootstrapClassLoaderSearch(const char* segment) {

which calls	

ClassPathZipEntry* ClassLoader::create_class_path_zip_entry(const char *path, bool is_boot_append) {

..which calls
		
char* ClassLoader::get_canonical_path(const char* orig, Thread* thread) {

...which makes a copy of the string:
  char* orig_copy = NEW_RESOURCE_ARRAY_IN_THREAD(thread, char, strlen(orig)+1);
  strcpy(orig_copy, orig);
...and doesn't apear to keep the pointer.  So yes I think we should free it. 8-)

-------------

PR: https://git.openjdk.java.net/jdk/pull/3751