From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:41200) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UWAlq-0004tz-0q for qemu-devel@nongnu.org; Sat, 27 Apr 2013 15:26:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UWAln-0002tU-FJ for qemu-devel@nongnu.org; Sat, 27 Apr 2013 15:26:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19490) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UWAln-0002tP-7H for qemu-devel@nongnu.org; Sat, 27 Apr 2013 15:26:51 -0400 Date: Sat, 27 Apr 2013 22:26:42 +0300 From: "Michael S. Tsirkin" Message-ID: <20130427192642.GA30188@redhat.com> References: <1366965244-20542-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1366965244-20542-1-git-send-email-jasowang@redhat.com> Subject: Re: [Qemu-devel] [PATCH 1/3] virtio-pci: 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, pmatouse@redhat.com, qemu-devel@nongnu.org On Fri, Apr 26, 2013 at 04:34:02PM +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 Why do this in virtio-pci and not in virtio.c? If instead we correct the checks in virtio.c we get less code, and all transports will benefit automatically. > --- > hw/virtio/virtio-pci.c | 9 +++++++++ > hw/virtio/virtio.c | 18 ------------------ > 2 files changed, 9 insertions(+), 18 deletions(-) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index a1f15a8..7f6c7d1 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -400,6 +400,10 @@ static uint64_t virtio_pci_config_read(void *opaque, hwaddr addr, > } > addr -= config; > > + if (addr + size > proxy->vdev->config_len) { > + return (uint32_t)-1; > + } > + > switch (size) { > case 1: > val = virtio_config_readb(proxy->vdev, addr); > @@ -430,6 +434,11 @@ static void virtio_pci_config_write(void *opaque, hwaddr addr, > return; > } > addr -= config; > + > + if (addr + size > proxy->vdev->config_len) { > + return; > + } > + > /* > * Virtio-PCI is odd. Ioports are LE but config space is target native > * endian. > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 1c2282c..3397b5e 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -563,9 +563,6 @@ uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr) > > vdev->get_config(vdev, vdev->config); > > - if (addr > (vdev->config_len - sizeof(val))) > - return (uint32_t)-1; > - > val = ldub_p(vdev->config + addr); > return val; > } > @@ -576,9 +573,6 @@ uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr) > > vdev->get_config(vdev, vdev->config); > > - if (addr > (vdev->config_len - sizeof(val))) > - return (uint32_t)-1; > - > val = lduw_p(vdev->config + addr); > return val; > } > @@ -589,9 +583,6 @@ uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr) > > vdev->get_config(vdev, vdev->config); > > - if (addr > (vdev->config_len - sizeof(val))) > - return (uint32_t)-1; > - > val = ldl_p(vdev->config + addr); > return val; > } > @@ -600,9 +591,6 @@ void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data) > { > uint8_t val = data; > > - if (addr > (vdev->config_len - sizeof(val))) > - return; > - > stb_p(vdev->config + addr, val); > > if (vdev->set_config) > @@ -613,9 +601,6 @@ void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data) > { > uint16_t val = data; > > - if (addr > (vdev->config_len - sizeof(val))) > - return; > - > stw_p(vdev->config + addr, val); > > if (vdev->set_config) > @@ -626,9 +611,6 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data) > { > uint32_t val = data; > > - if (addr > (vdev->config_len - sizeof(val))) > - return; > - > stl_p(vdev->config + addr, val); > > if (vdev->set_config) > -- > 1.7.1