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    Subject[PATCH V3 02/10] virtio_console: validate max_nr_ports before trying to use it
    Date
    We calculate nr_ports based on the max_nr_ports:

    nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;

    If the device advertises a large max_nr_ports, we will end up with a
    integer overflow. Fixing this by validating the max_nr_ports and fail
    the probe for invalid max_nr_ports in this case.

    Cc: Amit Shah <amit@kernel.org>
    Signed-off-by: Jason Wang <jasowang@redhat.com>
    ---
    drivers/char/virtio_console.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
    index 7eaf303a7a86..660c5c388c29 100644
    --- a/drivers/char/virtio_console.c
    +++ b/drivers/char/virtio_console.c
    @@ -28,6 +28,7 @@
    #include "../tty/hvc/hvc_console.h"

    #define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
    +#define VIRTCONS_MAX_PORTS 0x8000

    /*
    * This is a global struct for storing common data for all the devices
    @@ -2036,6 +2037,14 @@ static int virtcons_probe(struct virtio_device *vdev)
    virtio_cread_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
    struct virtio_console_config, max_nr_ports,
    &portdev->max_nr_ports) == 0) {
    + if (portdev->max_nr_ports == 0 ||
    + portdev->max_nr_ports > VIRTCONS_MAX_PORTS) {
    + dev_err(&vdev->dev,
    + "Invalidate max_nr_ports %d",
    + portdev->max_nr_ports);
    + err = -EINVAL;
    + goto free;
    + }
    multiport = true;
    }

    --
    2.25.1
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