sd_varlink_call_full() returns borrowed references into the varlink
connection's receive buffer (v->current). fetch_machine() stored this
borrowed reference with _cleanup_(sd_json_variant_unrefp), which would
unref it on error paths -- potentially freeing the parent object while
the varlink connection still owns it. On success, TAKE_PTR passed the
raw borrowed pointer to the caller, but the varlink connection (and its
receive buffer) is freed when fetch_machine returns, leaving the caller
with a dangling pointer.
Fix by removing the cleanup attribute (the reference is borrowed, not
owned) and taking a real ref via sd_json_variant_ref() before returning
to the caller, so the data survives the varlink connection's cleanup.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Christian Brauner
26a9ed9559