From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:34208) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UZcx2-0003JI-7m for qemu-devel@nongnu.org; Tue, 07 May 2013 04:08:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UZcwz-0006z1-JF for qemu-devel@nongnu.org; Tue, 07 May 2013 04:08:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60342) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UZcwz-0006yu-BK for qemu-devel@nongnu.org; Tue, 07 May 2013 04:08:41 -0400 Date: Tue, 7 May 2013 11:08:33 +0300 From: "Michael S. Tsirkin" Message-ID: <20130507080833.GA18456@redhat.com> References: <1367905369-10765-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1367905369-10765-1-git-send-email-jasowang@redhat.com> Subject: Re: [Qemu-devel] [PATCH V2] virtio: properly validate address before accessing config List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: aliguori@us.ibm.com, Petr Matousek , qemu-devel@nongnu.org On Tue, May 07, 2013 at 01:42:49PM +0800, Jason Wang wrote: > There are several several issues in the current checking: > > - The check was based on the minus of unsigned values which can overflow > - It was done after .{set|get}_config() which can lead crash when config_len > is zero since vdev->config is NULL > > Fix this by: > > - Validate the address in virtio_pci_config_{read|write}() before > .{set|get}_config > - Use addition instead minus to do the validation > > Cc: Michael S. Tsirkin > Cc: Petr Matousek > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin > --- > Changes from V1: > - Doing check in virtio.c instead of virtio-pci.c > - Drop the patch of virtio-ccw and s390-virtio-bus > --- > hw/virtio/virtio.c | 30 ++++++++++++++++++------------ > 1 files changed, 18 insertions(+), 12 deletions(-) > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 53a0d90..8176c14 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -568,10 +568,11 @@ uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr) > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > uint8_t val; > > - k->get_config(vdev, vdev->config); > - > - if (addr > (vdev->config_len - sizeof(val))) > + if (addr + sizeof(val) > vdev->config_len) { > return (uint32_t)-1; > + } > + > + k->get_config(vdev, vdev->config); > > val = ldub_p(vdev->config + addr); > return val; > @@ -582,10 +583,11 @@ uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr) > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > uint16_t val; > > - k->get_config(vdev, vdev->config); > - > - if (addr > (vdev->config_len - sizeof(val))) > + if (addr + sizeof(val) > vdev->config_len) { > return (uint32_t)-1; > + } > + > + k->get_config(vdev, vdev->config); > > val = lduw_p(vdev->config + addr); > return val; > @@ -596,10 +598,11 @@ uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr) > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > uint32_t val; > > - k->get_config(vdev, vdev->config); > - > - if (addr > (vdev->config_len - sizeof(val))) > + if (addr + sizeof(val) > vdev->config_len) { > return (uint32_t)-1; > + } > + > + k->get_config(vdev, vdev->config); > > val = ldl_p(vdev->config + addr); > return val; > @@ -610,8 +613,9 @@ void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data) > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > uint8_t val = data; > > - if (addr > (vdev->config_len - sizeof(val))) > + if (addr + sizeof(val) > vdev->config_len) { > return; > + } > > stb_p(vdev->config + addr, val); > > @@ -625,8 +629,9 @@ void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data) > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > uint16_t val = data; > > - if (addr > (vdev->config_len - sizeof(val))) > + if (addr + sizeof(val) > vdev->config_len) { > return; > + } > > stw_p(vdev->config + addr, val); > > @@ -640,8 +645,9 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data) > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > uint32_t val = data; > > - if (addr > (vdev->config_len - sizeof(val))) > + if (addr + sizeof(val) > vdev->config_len) { > return; > + } > > stl_p(vdev->config + addr, val); > > -- > 1.7.1