[foreign-memaccess+abi] RFR: 8294309: Downcall and Upcall unboxing code should reject heap segments

[Maurizio Cimadamore]

On Mon, 3 Oct 2022 21:16:41 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

> Recently I noticed that we don't check for heap segments anymore when unboxing memory segments to be passed to native code as addresses. This allows someone to pass a heap segment, which will be unboxed simply by calling `MemorySegment::address` which for heap segments returns the byte offset into the array. This is of course not a valid pointer.
> 
> This patch changes the unboxing logic to reject heap segments with an `IllegalArgumentException`.

src/java.base/share/classes/jdk/internal/foreign/abi/SharedUtils.java line 265:

> 263: 
> 264:     static long unboxSegment(MemorySegment segment) {
> 265:         if (segment instanceof HeapMemorySegmentImpl) {

there's MemorySegment.isNative, which maybe is better?

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

PR: https://git.openjdk.org/panama-foreign/pull/737