RFR: 8300491: SymbolLookup::libraryLookup accepts strings with terminators

[Paul Sandoz]

On Wed, 24 May 2023 15:22:15 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> There is a difference in behavior between `System::loadLibrary` and `SymbolLookup::libraryLookup(String)`. While the former catches library names containing NULL chars (because, internally it uses Path/File logic, which reject those), `SymbolLookup` does not. As a result, it is possible to load libraries such as `libGL.so\0foobar`, because the string is passed directly to `dlopen`.
> 
> A similar issue arises when we consider `SymbolLookup::find`, as the name is again sent unmodified to `dlopen`. In reality, some filtering *does* happen in that case, as the native code calls `GetStringUTFChars`:
> 
> https://docs.oracle.com/en/java/javase/20/docs/specs/jni/functions.html#getstringutfchars
> 
> Which encodes the NULL chars in a different form:
> 
> https://docs.oracle.com/en/java/javase/20/docs/specs/jni/types.html#modified-utf-8-strings
> 
> So, in practice, even if the input is not validated, a call to `find` with one or more NULL chars is unlikely to succeed.
> 
> In this patch I have added several checks to make sure that:
> * the name of library passed to `libraryLookup(String)` does not contain `\0` and, if so, throw `IllegalArgumentException` (which is already covered by current spec;
> * the name of a symbol passed to `SymbolLookup::find` does not contain `\0` and, if so, return empty optional. This required changes on all the lookups we implement.

Do you also need to test on `SymbolLookup` returned from `Linker::defaultLookup`?

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PR Review: https://git.openjdk.org/jdk/pull/14126#pullrequestreview-1442329856