Error when creating external buffers: Check failed: length == backing_store->byte_length()

[ZFail]

• Version: 13.3.0
• Platform: Windows7 x64 and Ubuntu18 x64

What steps will reproduce the bug?

Error occurs when creating external buffer (node::Buffer::New) over existing node buffer with different size, this mechanism is used in the node-ffi library.
Simple reproducer:

git clone https://github.com/ZFail/node-addon-examples
cd node-addon-examples
git checkout d1b2b7505337411ecfdcdf1d6bfc4d1aaa923a1f
cd 2_function_arguments
cd node-addon-api
yarn install
node addon.js

What is the expected behavior?

output must be:

This should be 0123456789012345: 0123456789012345
This should be 01: 01
This should be 0123: 0123

What do you see instead?

This should be 0123456789012345: 0123456789012345


#
# Fatal error in , line 0
# Check failed: length == backing_store->byte_length().
#
#
#
#FailureMessage Object: 00000000001ADF80

Additional information

Seems like an error in the LookupOrCreateBackingStore function in v8. We should not do a BackingStore lookup for an external buffer.
https://github.com/nodejs/node/blob/master/deps/v8/src/api/api.cc#L7281

[addaleax]

Error occurs when creating external buffer (node::Buffer::New) over existing node buffer with different size, this mechanism is used in the node-ffi library.

Fwiw, I maintain an N-API port of this library at https://github.com/node-ffi-napi/node-ffi-napi/. This is a breaking change in V8, and likely one that we will have to live with. I haven’t gotten around to fixing this for the N-API port yet – it’s not trivial, but it should be doable. But generally, this is a problem that will need to be addressed in the addons that perform these kinds of operations.

[ZFail]

I don't think that this problem can be solved in add-ons. If the pointer comes from an external library, we can't know if it points to an existing node buffer, but we must give access to this part of memory from js.

[targos]

What do you suggest Node.js can do?

[targos]

Closing as there was no follow-up.