[alsa-devel] [PATCH] hda: add bounds checking for the codec command fields

[Wu Fengguang]

On Fri, Jul 17, 2009 at 04:24:10PM +0800, Wu Fengguang wrote:
> A recent bug involves passing auto detected >0x7f NID to codec command,
> creating an invalid codec addr field, and finally lead to cmd timeout
> and fall back into single command mode. Jaroslav fixed that bug in
> alc880_parse_auto_config().
> 
> It would be safer to further check the bounds of all cmd fields.
> 
> Cc: Jaroslav Kysela <perex at perex.cz>
> Signed-off-by: Wu Fengguang <fengguang.wu at intel.com>
> ---
> diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> index 462e2ce..7d09650 100644
> --- a/sound/pci/hda/hda_codec.c
> +++ b/sound/pci/hda/hda_codec.c
> @@ -150,6 +150,16 @@ make_codec_cmd(struct hda_codec *codec, hda_nid_t nid, int direct,
>  {
>  	u32 val;
>  
> +	if ((direct & ~1) || (nid & ~0x7f) ||
> +	    (verb & ~0xfff) || (parm & ~0xff)) {
> +		printk(KERN_ERR "hda-codec: out of range cmd %x:%x:%x:%x:%x\n",
> +		       codec->addr, direct, nid, verb, parm);

Maybe we shall simply return here?

> +		direct &= 1;
> +		nid  &= 0x7f;
> +		verb &= 0xfff;
> +		parm &= 0xff;
> +	}
> +
>  	val = (u32)(codec->addr & 0x0f) << 28;
>  	val |= (u32)direct << 27;
>  	val |= (u32)nid << 20;