Re: [Qemu-devel] [PATCH] nvme: fix oob access issue(CVE-2018-16847)

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 2/11/18 2:22, Li Qiang wrote:
> Currently, the nvme_cmb_ops mr doesn't check the addr and size.
> This can lead an oob access issue. This is triggerable in the guest.
> Add check to avoid this issue.
> 
> Fixes CVE-2018-16847.
> 
> Reported-by: Li Qiang <liq3ea@gmail.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Li Qiang <liq3ea@gmail.com>
> ---
>   hw/block/nvme.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index fc7dacb..d097add 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -1175,6 +1175,10 @@ static void nvme_cmb_write(void *opaque, hwaddr addr, uint64_t data,
>       unsigned size)
>   {
>       NvmeCtrl *n = (NvmeCtrl *)opaque;
> +
> +    if (addr + size > NVME_CMBSZ_GETSIZE(n->bar.cmbsz)) {

Should this be reported via qemu_log_mask(LOG_GUEST_ERROR, ...)?

> +        return;
> +    }
>       memcpy(&n->cmbuf[addr], &data, size);
>   }
>   
> @@ -1183,6 +1187,9 @@ static uint64_t nvme_cmb_read(void *opaque, hwaddr addr, unsigned size)
>       uint64_t val;
>       NvmeCtrl *n = (NvmeCtrl *)opaque;
>   
> +    if (addr + size > NVME_CMBSZ_GETSIZE(n->bar.cmbsz)) {

Ditto.

> +        return 0;
> +    }
>       memcpy(&val, &n->cmbuf[addr], size);
>       return val;
>   }
>