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Re: [Qemu-arm] [Qemu-devel] [PATCH v4] char: cadence: check baud rate ge
From: |
Alistair Francis |
Subject: |
Re: [Qemu-arm] [Qemu-devel] [PATCH v4] char: cadence: check baud rate generator and divider values |
Date: |
Fri, 28 Oct 2016 08:34:05 -0700 |
On Thu, Oct 27, 2016 at 12:24 PM, P J P <address@hidden> wrote:
> From: Prasad J Pandit <address@hidden>
>
> The Cadence UART device emulator calculates speed by dividing the
> baud rate by a 'baud rate generator' & 'baud rate divider' value.
> The device specification defines these register values to be
> non-zero and within certain limits. Add checks for these limits
> to avoid errors like divide by zero.
>
> Reported-by: Huawei PSIRT <address@hidden>
> Signed-off-by: Prasad J Pandit <address@hidden>
This looks good to me. I'll spin up a new patch for the migration fix
next week (I won't have time today).
Reviewed-by: Alistair Francis <address@hidden>
Thanks,
Alistair
> ---
> hw/char/cadence_uart.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> Update: remove default reset value assignment.
> -> https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg07206.html
>
> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
> index e3bc52f..4a3c4c6 100644
> --- a/hw/char/cadence_uart.c
> +++ b/hw/char/cadence_uart.c
> @@ -1,6 +1,11 @@
> /*
> * Device model for Cadence UART
> *
> + * Reference: Xilinx Zynq 7000 reference manual
> + * -
> http://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000-TRM.pdf
> + * - Chapter 19 UART Controller
> + * - Appendix B for Register details
> + *
> * Copyright (c) 2010 Xilinx Inc.
> * Copyright (c) 2012 Peter A.G. Crosthwaite (address@hidden)
> * Copyright (c) 2012 PetaLogix Pty Ltd.
> @@ -410,6 +415,16 @@ static void uart_write(void *opaque, hwaddr offset,
> break;
> }
> break;
> + case R_BRGR: /* Baud rate generator */
> + if (value >= 0x01) {
> + s->r[offset] = value & 0xFFFF;
> + }
> + break;
> + case R_BDIV: /* Baud rate divider */
> + if (value >= 0x04) {
> + s->r[offset] = value & 0xFF;
> + }
> + break;
> default:
> s->r[offset] = value;
> }
> --
> 2.7.4
>
>