Re: [Qemu-devel] [PATCH] audio: fix integer overflow expression

[Andreas Färber]

Am 31.05.2011 um 19:28 schrieb Peter Maydell:

> From: Juha Riihimäki <address@hidden>
>
> Fix an integer overflow that can happen for signed 32 bit types
> when using FLOAT_MIXENG. (Note that at the moment this is only true
> when using the MacOSX coreaudio audio driver.)

Missing Riku's SoB compared to the link you gave below!

> Signed-off-by: Juha Riihimäki <address@hidden>
> Reviewed-by: Peter Maydell <address@hidden>
> ---
> I'm trying to get random patches out of my patch-stack and upstream.
> This one looks "obviously correct" but it only kicks in for MacOSX
> and coreaudio, and I don't have access to that platform to test  
> myself,
> so treat my reviewed-by accordingly.

The warnings I get on v10.5 ppc64 are as follows:

  CC    audio/mixeng.o
In file included from /Users/andreas/QEMU/qemu/audio/mixeng.c:112:
/Users/andreas/QEMU/qemu/audio/mixeng_template.h: In function  
‘conv_natural_int32_t’:
/Users/andreas/QEMU/qemu/audio/mixeng_template.h:49: warning: integer  
overflow in expression
/Users/andreas/QEMU/qemu/audio/mixeng_template.h: In function  
‘clip_natural_int32_t’:
/Users/andreas/QEMU/qemu/audio/mixeng_template.h:66: warning: integer  
overflow in expression
In file included from /Users/andreas/QEMU/qemu/audio/mixeng.c:117:
/Users/andreas/QEMU/qemu/audio/mixeng_template.h: In function  
‘conv_swap_int32_t’:
/Users/andreas/QEMU/qemu/audio/mixeng_template.h:49: warning: integer  
overflow in expression
/Users/andreas/QEMU/qemu/audio/mixeng_template.h: In function  
‘clip_swap_int32_t’:
/Users/andreas/QEMU/qemu/audio/mixeng_template.h:66: warning: integer  
overflow in expression

I confirm that this patch silences these. Will test the new patch  
right away.

> This has actually been posted here before, last year:
> http://patchwork.ozlabs.org/patch/48703/

That patch clearly shows that dumping a large and unrelated patch  
series onto the mailing list without cc'ing people and never following  
them up is not a winning strategy.

Andreas

> audio/mixeng_template.h |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/audio/mixeng_template.h b/audio/mixeng_template.h
> index a2d0ef8..e01da0a 100644
> --- a/audio/mixeng_template.h
> +++ b/audio/mixeng_template.h
> @@ -46,7 +46,7 @@ static mixeng_real inline glue (conv_, ET) (IN_T v)
> #endif
> #else  /* !RECIPROCAL */
> #ifdef SIGNED
> -    return nv / (mixeng_real) (IN_MAX - IN_MIN);
> +    return nv / (mixeng_real) ((mixeng_real)IN_MAX -  
> (mixeng_real)IN_MIN);
> #else
>     return (nv - HALF) / (mixeng_real) IN_MAX;
> #endif
> @@ -63,7 +63,7 @@ static IN_T inline glue (clip_, ET) (mixeng_real v)
>     }
>
> #ifdef SIGNED
> -    return ENDIAN_CONVERT ((IN_T) (v * (IN_MAX - IN_MIN)));
> +    return ENDIAN_CONVERT ((IN_T) (v * ((mixeng_real)IN_MAX -  
> (mixeng_real)IN_MIN)));
> #else
>     return ENDIAN_CONVERT ((IN_T) ((v * IN_MAX) + HALF));
> #endif
> --
> 1.7.1