533311 - const slots are not actually const

Status: RESOLVED WONTFIX

(Tamarin Graveyard :: Virtual Machine, enhancement)

Description

[Christopher A. Brichford]

Attachment: Abc that implements a loop that uses a const slot as a counter.

initproperty instructions can be used to update slots in a constructor, including slots on instances that have already be constructed.  Arguably initproperty should only be able to update an instance that is being constructed.

If we want to fix I think the right way to fix  
this is to cause the verifier to disallow writes of local0 ( which has  
the this pointer ) and then change the initproperty instruction to  
always use local0 as the base instead of popping the base off the  
stack.  initproperty should only be able to use fully static names  
that refer to const slots.  initproperty should not be allowed to  
initialize non-const slots ( that's what setproperty is for ).  With  
these new constraints the verifier should be able to do all the  
validation that is needed to safely execute initproperty instructions.