Re: [Qemu-devel] [PATCH] virtio: do not take address of packed members

[Philippe Mathieu-Daudé]

On 9/26/18 11:20 PM, Paolo Bonzini wrote:
> The address of a packed member is not packed, which may cause accesses
> to unaligned pointers.  Avoid this by reading the packed value before
> passing it to another function.
> 
> Cc: Jason Wang <address@hidden>
> Cc: Peter Maydell <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> Cc: address@hidden
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>         Resubmission of the patch at 
> https://patchwork.kernel.org/patch/10160229/
>         The vhost part has since been fixed independently (commit
>         69aff03064, "vhost-user: fix misaligned access to payload",
>         2018-01-18).
> 
>  hw/char/virtio-serial-bus.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index d2dd8ab502..04e3ebe352 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -667,9 +667,9 @@ static void virtio_serial_save_device(VirtIODevice *vdev, 
> QEMUFile *f)
>  
>      /* The config space (ignored on the far end in current versions) */
>      get_config(vdev, (uint8_t *)&config);
> -    qemu_put_be16s(f, &config.cols);
> -    qemu_put_be16s(f, &config.rows);
> -    qemu_put_be32s(f, &config.max_nr_ports);
> +    qemu_put_be16(f, config.cols);
> +    qemu_put_be16(f, config.rows);
> +    qemu_put_be32(f, config.max_nr_ports);

Clever.

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

>  
>      /* The ports map */
>      max_nr_ports = s->serial.max_virtserial_ports;
>