Re: [PATCH] amixer: add support for TLV byte control read

[Vinod Koul <vinod.koul@intel.com>]

On Thu, Jan 28, 2016 at 05:19:21PM +0100, Takashi Iwai wrote:
> The line number doesn't match with the latest code in git, so
> double-check that the problem happens with the latest alsa-lib and
> alsa-utils, too.

I am on debian packages 1.0.27

> I'm thinking whether this is rather an issue in the kernel driver
> side.  In skl_tplg_tlv_control_get(),

I think you are right, the buffer would overflow which would cause heap to
go bad and free goes crashing

> 
> 	if (bc->params) {
> 		if (copy_to_user(data, &bc->param_id, sizeof(u32)))
> 			return -EFAULT;
> 		if (copy_to_user(data + 1, &size, sizeof(u32)))
> 			return -EFAULT;
> 		if (copy_to_user(data + 2, bc->params, size))
> 			return -EFAULT;
> 	}
> 
> But here, size is the size of the whole container, not the size in the
> container.  In the code above, you're copying size+8 bytes total and
> this breaks the boundary already.

Right, also I think we need to check for size vs size of parameters. We
don't want to copy kernel memory to usermode if usermode gave a larger
buffer

Let me test this, thanks for pointing

-- 
~Vinod