That is incorrect about function pointers: The VM does check that you are calling the right function type, and it will trap if the type does not match.

Here it is in the spec:

> The call_indirect instruction calls a function indirectly through an operand indexing into a table that is denoted by a table index and must have type funcref. Since it may contain functions of heterogeneous type, the callee is dynamically checked against the function type indexed by the instruction’s second immediate, and the call is aborted with a trap if it does not match.

From https://www.w3.org/TR/wasm-core-2/#syntax-instr-control

(Other sandboxing approaches, including related ones like asm.js, do other things, some closer to what you mentioned. But wasm has strict checking here.)

Hmm, I wonder if I was confusing emscripten's asm.js approach with its approach to Wasm. Thank you!