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Re: [Qemu-ppc] [PATCH] spapr-vty: Fix bad assert() statement
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-ppc] [PATCH] spapr-vty: Fix bad assert() statement |
Date: |
Thu, 10 Nov 2016 15:41:37 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 10/11/2016 10:06, Thomas Huth wrote:
> When using the serial console in the GTK interface of QEMU (and
> QEMU has been compiled with CONFIG_VTE), it is possible to trigger
> the assert() statement in vty_receive() in spapr_vty.c by pasting
> a chunk of text with length > 16 into the QEMU window.
> Most of the other serial backends seem to simply drop characters
> that they can not handle, so I think we should also do the same in
> spapr-vty to fix this issue. And since it is quite ugly when pasted
> text is chopped after 16 bytes, we also increase the size of the
> input buffer here so that we can at least handle a couple of text
> lines.
>
> Buglink: https://bugs.launchpad.net/qemu/+bug/1639322
> Signed-off-by: Thomas Huth <address@hidden>
> ---
> hw/char/spapr_vty.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/hw/char/spapr_vty.c b/hw/char/spapr_vty.c
> index 31822fe..bee6c34 100644
> --- a/hw/char/spapr_vty.c
> +++ b/hw/char/spapr_vty.c
> @@ -1,4 +1,5 @@
> #include "qemu/osdep.h"
> +#include "qemu/error-report.h"
> #include "qapi/error.h"
> #include "qemu-common.h"
> #include "cpu.h"
> @@ -7,7 +8,7 @@
> #include "hw/ppc/spapr.h"
> #include "hw/ppc/spapr_vio.h"
>
> -#define VTERM_BUFSIZE 16
> +#define VTERM_BUFSIZE 2048
This change causes a change in the migration protocol.
Paolo
>
> typedef struct VIOsPAPRVTYDevice {
> VIOsPAPRDevice sdev;
> @@ -37,7 +38,15 @@ static void vty_receive(void *opaque, const uint8_t *buf,
> int size)
> qemu_irq_pulse(spapr_vio_qirq(&dev->sdev));
> }
> for (i = 0; i < size; i++) {
> - assert((dev->in - dev->out) < VTERM_BUFSIZE);
> + if (dev->in - dev->out >= VTERM_BUFSIZE) {
> + static bool reported;
> + if (!reported) {
> + error_report("VTY input buffer exhausted - characters
> dropped."
> + " (input size = %i)", size);
> + reported = true;
> + }
> + break;
> + }
> dev->buf[dev->in++ % VTERM_BUFSIZE] = buf[i];
> }
> }
>