From 5f5a1318653c08e435cfa52f60b6a712815b659d Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Tue, 7 May 2013 13:42:49 +0800 Subject: virtio: properly validate address before accessing config 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 Acked-by: Petr Matousek Message-id: 1367905369-10765-1-git-send-email-jasowang@redhat.com Signed-off-by: Anthony Liguori --- hw/virtio/virtio.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 53a0d90468..8176c147e1 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); -- cgit v1.2.3