virtio-balloon: Tweak recent fix for integer overflow

Commit 1f9296b avoids "other kinds of overflow" by limiting the
polling interval to UINT_MAX.  The computations to protect are done in
64 bits.  This is indeed safe when unsigned is 32 bits, as it commonly
is.  It isn't when unsigned is 64 bits.  Purely theoretical; I'm not
aware of such a system.  Limit it to UINT32_MAX instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index b5cf7cacc09a033b1c15a27f454079b072acca88..7bfbb75ad3fdbd0e2c9600873bc46f8aaea5df97 100644 (file)
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -170,7 +170,7 @@ static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
         return;
     }
 
-    if (value > UINT_MAX) {
+    if (value > UINT32_MAX) {
         error_setg(errp, "timer value is too big");
         return;
     }