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Date: Wed, 29 Aug 2012 20:57:47 +0200
From: Stefan Weil <sw@weilnetz.de>
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Subject: Re: [Qemu-devel] [PATCH for-1.2] hw/arm_gic.c: Define .class_size
 in arm_gic_info TypeInfo
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, patches@linaro.org

Am 29.08.2012 09:52, schrieb Peter Maydell:
> Add the missing .class_size definition to the arm_gic_info TypeInfo.
> This fixes the memory corruption and possible segfault that otherwise
> results when the class struct is allocated at too small a size and
> the class init function writes off the end of it.
>
> Reported-by: Adam Lackorzynski<adam@os.inf.tu-dresden.de>
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
> Oops. I suspect this only crashes on 32 bit hosts because the class
> is only one field larger than its subclass, so on 64 bit systems
> we are probably only overwriting padding rather than anything
> important. For 1.2 since it fixes a segfault.
>
>   hw/arm_gic.c |    1 +
>   1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/hw/arm_gic.c b/hw/arm_gic.c
> index 186ac66..55871fa 100644
> --- a/hw/arm_gic.c
> +++ b/hw/arm_gic.c
> @@ -703,6 +703,7 @@ static TypeInfo arm_gic_info = {
>       .parent = TYPE_ARM_GIC_COMMON,
>       .instance_size = sizeof(gic_state),
>       .class_init = arm_gic_class_init,
> +    .class_size = sizeof(ARMGICClass),
>   };
>
>   static void arm_gic_register_types(void)

Tested-by: Stefan Weil <sw@weilnetz.de>

The patch fixes Valgrind error messages (tested on 64 bit Linux Debian 
Squeeze)
and segfaults (seen on 32 bit Linux Ubuntu Lenny and on 64 bit Windows).

Anthony, please apply it to QEMU 1.2.

Regards,

Stefan

PS. Are there perhaps more bugs of this sort? A quick test looking
for .class_init without .class_size shows a lot of files.