Re: [Qemu-devel] [PATCH 2/3] adlib: mark as insecure and deprecated.

[Thomas Huth]

On 2018-10-25 09:52, Gerd Hoffmann wrote:
> We have a lovely, guest-triggerable buffer overflow in opl2 emulation.
> 
> Reproducer:
>     outw(0xff60, 0x220);
>     outw(0x1020, 0x220);
>     outw(0xffb0, 0x220);
> Result:
>     Will overflow FM_OPL->AR_TABLE[] (see hw/audio/fmopl.[ch])
> 
> The specs google finds (http://www.symphoniae.com/Yamaha/YSC/YM3812.pdf)
> are rather sparse, possibly incomplete (looks like scanned fax with a
> scrambled page at the end) and not really helpful in identifying which
> of the register writes sets some illegal value.
> 
> So, go tag the device as deprecated with a warning messge, to notify
> users and schedule it for removal according to our deprecation policy.
> 
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  hw/audio/adlib.c     | 1 +
>  qemu-deprecated.texi | 4 ++++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/hw/audio/adlib.c b/hw/audio/adlib.c
> index 97b876c..fb4a29c 100644
> --- a/hw/audio/adlib.c
> +++ b/hw/audio/adlib.c
> @@ -311,6 +311,7 @@ static void adlib_class_initfn (ObjectClass *klass, void 
> *data)
>      set_bit(DEVICE_CATEGORY_SOUND, dc->categories);
>      dc->desc = ADLIB_DESC;
>      dc->props = adlib_properties;
> +    dc->deprecation_reason = "insecure, buffer overflow in opl2 emulation";
>  }
>  
>  static const TypeInfo adlib_info = {
> diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
> index 11b870c..7951a4f 100644
> --- a/qemu-deprecated.texi
> +++ b/qemu-deprecated.texi
> @@ -116,6 +116,10 @@ The @option{[hub_id name]} parameter tuple of the 
> 'hostfwd_add' and
>  The ``ivshmem'' device type is replaced by either the ``ivshmem-plain''
>  or ``ivshmem-doorbell`` device types.
>  
> address@hidden adlib (since 3.1)
> +
> +Has known buffer overflow.
> +
>  @section System emulator machines
>  
>  @subsection pc-0.10 and pc-0.11 (since 3.0)
> 

Any chance you could maybe at least add an assert() to the affected code
so that it crashes instead of silently overflowing the buffer?

Anyway, with the "messge" typo fixed:

Reviewed-by: Thomas Huth <address@hidden>