Re: [PATCH] meson: Stop if cfi is enabled with system slirp

[Paolo Bonzini]

On 04/03/21 11:37, Daniel P. Berrangé wrote:
> On Wed, Mar 03, 2021 at 09:59:38PM -0500, Daniele Buono wrote:
> > For CFI, we need to compile slirp as a static library together with qemu.
> > This is because we register slirp functions as callbacks for QEMU Timers.
> > When using a system-wide shared libslirp, the type information for the
> > callback is missing and the timer call produces a false positive with CFI.
>
> Is there work being done, or at least an active plan, for fixing this ?

Daniele, would this work (uncompiled even)?

diff --git a/net/slirp.c b/net/slirp.c
index be914c0be0..82e05d2c01 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -174,23 +174,42 @@ static int64_t net_slirp_clock_get_ns(void *opaque)
     return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 }

+typedef struct SlirpTimer {
+    QEMUTimer t;
+    SlirpTimerCb cb;
+    void *cb_opaque;
+} SlirpTimer;
+
+static void slirp_timer_cb(void *opaque)
+{
+    SlirpTimer *st = opaque;
+    st->cb(st->cb_opaque);
+}
+
 static void *net_slirp_timer_new(SlirpTimerCb cb,
                                  void *cb_opaque, void *opaque)
 {
-    return timer_new_full(NULL, QEMU_CLOCK_VIRTUAL,
-                          SCALE_MS, QEMU_TIMER_ATTR_EXTERNAL,
-                          cb, cb_opaque);
+    SlirpTimer *st = g_new(SlirpTimer, 1);
+    st->cb = cb;
+    st->cb_opaque = cb_opaque;
+    timer_init_full(&st->t, NULL, QEMU_CLOCK_VIRTUAL,
+                    SCALE_MS, QEMU_TIMER_ATTR_EXTERNAL,
+                    slirp_timer_cb, st);
+    return st;
 }

 static void net_slirp_timer_free(void *timer, void *opaque)
 {
-    timer_free(timer);
+    SlirpTimer *st = timer;
+    timer_del(&st->t);
+    g_free(st);
 }

 static void net_slirp_timer_mod(void *timer, int64_t expire_timer,
                                 void *opaque)
 {
-    timer_mod(timer, expire_timer);
+    SlirpTimer *st = timer;
+    timer_mod(&st->t, expire_timer);
 }

 static void net_slirp_register_poll_fd(int fd, void *opaque)