Re: [Qemu-devel] [PATCH 18/23] ssd0323: fix buffer overun on invalid state load

[Peter Maydell]

On 3 December 2013 16:29, Michael S. Tsirkin <address@hidden> wrote:
> CVE-2013-4538
>
> s->cmd_len used as index in ssd0323_transfer() to store 32-bit field.
> Possible this field might then be supplied by guest to overwrite a
> return addr somewhere. Same for row/col fields, which are indicies into
> framebuffer array.
>
> To fix validate after load.

The commit message says it validates the row/col fields...

> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  hw/display/ssd0323.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/hw/display/ssd0323.c b/hw/display/ssd0323.c
> index c3231c6..2c82598 100644
> --- a/hw/display/ssd0323.c
> +++ b/hw/display/ssd0323.c
> @@ -312,6 +312,9 @@ static int ssd0323_load(QEMUFile *f, void *opaque, int 
> version_id)
>          return -EINVAL;
>
>      s->cmd_len = qemu_get_be32(f);
> +    if (s->cmd_len < 0 || s->cmd_len > ARRAY_SIZE(s->cmd_data)) {
> +        return -EINVAL;
> +    }
>      s->cmd = qemu_get_be32(f);
>      for (i = 0; i < 8; i++)
>          s->cmd_data[i] = qemu_get_be32(f);
> --

...but the patch only checks the cmd_len ?

thanks
-- PMM