At Mon, 09 Jun 2014 16:46:32 -0400,
Wang, Xiaoming wrote:
>
>
> The size of struct snd_compr_avail is 0x1c in 32bit kernel,
> while it is 0x20 in 64bit kernel 0x4 bytes added because of
> alignment. It is OK when 32bit kernel met 32bit user space.
> There exist stack corruption if 64bit kernel met 32bit user
> space, because the size of struct snd_compr_avail is 0x1c
> in 32bit user space which is smaller than it will get from
> kernel. The extra 4 bytes can corrupt the stack, and
> introduce unpredictable error.
>
> Signed-off-by: Zhang Dongxing <[email protected]>
> Signed-off-by: xiaoming wang <[email protected]>
This would break the existing 32bit systems, so I don't think we can
take this approach.
Either break the 64bit systems (which aren't deployed yet much, so
far) by adding packed attribute, or implement 32/64 bit conversion in
compat_ioctl fop.
thanks,
Takashi
> ---
> include/uapi/sound/compress_offload.h | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/include/uapi/sound/compress_offload.h
> b/include/uapi/sound/compress_offload.h
> index 5759810..766b416 100644
> --- a/include/uapi/sound/compress_offload.h
> +++ b/include/uapi/sound/compress_offload.h
> @@ -70,6 +70,7 @@ struct snd_compr_tstamp {
> __u32 pcm_frames;
> __u32 pcm_io_frames;
> __u32 sampling_rate;
> + __u32 reserved[1];
> };
>
> /**
> --
> 1.7.1
>
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