From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55658) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9Y4M-0006hF-Gs for qemu-devel@nongnu.org; Tue, 22 Jul 2014 07:17:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X9Y49-0005UZ-DT for qemu-devel@nongnu.org; Tue, 22 Jul 2014 07:17:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36533) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9Y49-0005TA-4m for qemu-devel@nongnu.org; Tue, 22 Jul 2014 07:17:05 -0400 Date: Tue, 22 Jul 2014 16:46:17 +0530 From: Amit Shah Message-ID: <20140722111617.GD18209@grmbl.mre> References: <1405979077-18163-1-git-send-email-jsnow@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1405979077-18163-1-git-send-email-jsnow@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3] virtio-rng: Add human-readable error message for negative max-bytes parameter List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org, armbru@redhat.com On (Mon) 21 Jul 2014 [17:44:37], John Snow wrote: > If a negative integer is used for the max_bytes parameter, QEMU currently > calls abort() and leaves behind a core dump. This patch adds a simple > error message to make the reason for the termination clearer. > > There is an underlying insufficiency in the parameter parsing code of QEMU > that renders it unable to reject negative values for unsigned properties, > thus the error message "a non-negative integer below 2^63" is the most > user-friendly and correct message we can give until the underlying > insufficiency is corrected. > > Signed-off-by: John Snow > --- > v3: Adjusted the error message to be more semantically meaningful, but > while acknowledging the limitations of the current unsigned integer > parsing routines. > > hw/virtio/virtio-rng.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c > index 1356aca..7c5a675 100644 > --- a/hw/virtio/virtio-rng.c > +++ b/hw/virtio/virtio-rng.c > @@ -181,7 +181,13 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp) > > vrng->vq = virtio_add_queue(vdev, 8, handle_input); > > - assert(vrng->conf.max_bytes <= INT64_MAX); > + /* Workaround: Property parsing does not enforce unsigned integers, > + * So this is a hack to reject such numbers. */ > + if (vrng->conf.max_bytes > INT64_MAX) { > + error_set(errp, QERR_INVALID_PARAMETER_VALUE, "max-bytes", > + "a non-negative integer below 2^63"); Huh, why do we allow 0? There's no reason to have 0 as a max-bytes value as well... Amit