From: Carsten Beckmann <carsten_beckmann@genua.de>
Subject: dt(4): undefined behaviour for tracepoints
To: "tech@openbsd.org" <tech@openbsd.org>
Date: Wed, 24 Apr 2024 12:29:39 +0000

Hi,

I believe that the tracepoints for dt(4) cause undefined behaviour.
The tracepoint arguments are extracted in dt_prov_static_hook using
'va_arg(ap, uintptr_t)', so they are expected to be of type uintptr_t.
The different invocations of TRACEPOINT() use a wide variety of types
though without casting them to uintptr_t which to my understanding is
undefined behaviour.

I discovered this issue when I was seeing nonsensical values for
arguments in btrace and just wanted to let you know.

Carsten