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Date: Thu, 22 Nov 2018 15:52:12 +0000
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Message-ID: <20181122155212.GA2863@work-vm>
References: <20181122133207.29928-1-kraxel@redhat.com>
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In-Reply-To: <20181122133207.29928-1-kraxel@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] audio/hda: fix guest triggerable assert
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org

* Gerd Hoffmann (kraxel@redhat.com) wrote:
> Guest writes to a readonly register trigger the assert in
> intel_hda_reg_write().  Add a check and just ignore them.
> 
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1628433
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Does make you wonder:
  a) Why the guest was writing to a read-only register
  b) Wth it only did it in the weird combination of
     devices tested.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  hw/audio/intel-hda.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/hw/audio/intel-hda.c b/hw/audio/intel-hda.c
> index 23a2cf6484..066532713c 100644
> --- a/hw/audio/intel-hda.c
> +++ b/hw/audio/intel-hda.c
> @@ -929,6 +929,10 @@ static void intel_hda_reg_write(IntelHDAState *d, const IntelHDAReg *reg, uint32
>      if (!reg) {
>          return;
>      }
> +    if (!reg->wmask) {
> +        /* read-only register */
> +        return;
> +    }
>  
>      if (d->debug) {
>          time_t now = time(NULL);
> -- 
> 2.9.3
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK