Re: [PATCH v2] hw/net/can: sja1000 fix buff2frame_bas and buff2frame_pel when dlc is out of std CAN 8 bytes

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

"hw/net/can: sja1000 fix buff2frame* when dlc is out of std CAN 8 bytes"

On 7/29/21 2:33 PM, Pavel Pisa wrote:
> Problem reported by openEuler fuzz-sig group.
> 
> The buff2frame_bas function (hw\net\can\can_sja1000.c)
> infoleak(qemu5.x~qemu6.x) or stack-overflow(qemu 4.x).

Cc: qemu-stable@nongnu.org

> Reported-by: Qiang Ning <ningqiang1@huawei.com>
> Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
>  hw/net/can/can_sja1000.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/hw/net/can/can_sja1000.c b/hw/net/can/can_sja1000.c
> index 42d2f99dfb..34eea684ce 100644
> --- a/hw/net/can/can_sja1000.c
> +++ b/hw/net/can/can_sja1000.c
> @@ -275,6 +275,10 @@ static void buff2frame_pel(const uint8_t *buff, qemu_can_frame *frame)
>      }
>      frame->can_dlc = buff[0] & 0x0f;
>  
> +    if (frame->can_dlc > 8) {
> +        frame->can_dlc = 8;
> +    }
> +
>      if (buff[0] & 0x80) { /* Extended */
>          frame->can_id |= QEMU_CAN_EFF_FLAG;
>          frame->can_id |= buff[1] << 21; /* ID.28~ID.21 */
> @@ -311,6 +315,10 @@ static void buff2frame_bas(const uint8_t *buff, qemu_can_frame *frame)
>      }
>      frame->can_dlc = buff[1] & 0x0f;
>  
> +    if (frame->can_dlc > 8) {
> +        frame->can_dlc = 8;
> +    }
> +
>      for (i = 0; i < frame->can_dlc; i++) {
>          frame->data[i] = buff[2 + i];
>      }
>