From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:42459) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UWMRO-0005pc-AJ for qemu-devel@nongnu.org; Sun, 28 Apr 2013 03:54:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UWMRN-00046C-4Y for qemu-devel@nongnu.org; Sun, 28 Apr 2013 03:54:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48580) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UWMRM-000464-TV for qemu-devel@nongnu.org; Sun, 28 Apr 2013 03:54:33 -0400 Message-ID: <517CD5AC.2080708@redhat.com> Date: Sun, 28 Apr 2013 15:54:20 +0800 From: Jason Wang MIME-Version: 1.0 References: <1366965244-20542-1-git-send-email-jasowang@redhat.com> <20130427192642.GA30188@redhat.com> In-Reply-To: <20130427192642.GA30188@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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: "Michael S. Tsirkin" Cc: aliguori@us.ibm.com, pmatouse@redhat.com, qemu-devel@nongnu.org On 04/28/2013 03:26 AM, Michael S. Tsirkin wrote: > 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. I wish I could but looks like vitio_config_read{b|w|l} were only used by virtio-pci. Other transport such as ccw and s390-virtio-bus have their own implementation. > >> --- >> 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