Re: rpcrt4: Fix regression in NdrConformantStringUnmarshall by doing the memcpy check in safe_copy_from_buffer

[Robert Shearman]

Maarten Lankhorst wrote:
> Hi Rob,
>
> Robert Shearman schreef:
> > Maarten Lankhorst wrote:
> > > @@ -665,7 +665,8 @@ static inline void
> > > safe_copy_from_buffer(MIDL_STUB_MESSAGE *pStubMsg, void *p, U
> > >      if ((pStubMsg->Buffer + size < pStubMsg->Buffer) || /* integer
> > > overflow of pStubMsg->Buffer */
> > >          (pStubMsg->Buffer + size > pStubMsg->BufferEnd))
> > >          RpcRaiseException(RPC_X_BAD_STUB_DATA);
> > > - memcpy(p, pStubMsg->Buffer, size);
> > > - if (p != pStubMsg->Buffer)
> > > -
> > >    memcpy(p, pStubMsg->Buffer, size);
> > > pStubMsg->Buffer += size;
> > >
> > > }
> >
> > Good work in spotting and fixing the mistake I made, but I think I'd
> > prefer to fix it by making the caller of safe_copy_from_buffer do the
> > incrementing of the buffer. This is to avoid confusion with the name
> > of the function and to avoid the possibility that the buffer is
> > incremented twice.
>
> If you want to remove that, you might as well remove that whole inline,
> since even when the two areas are equal the check that needs to be
> performed at overflowing still needs to be done even if the areas are
> the same.

That's what safe_buffer_increment does.