[alsa-devel] [PATCH v2] control_hw: Fix issue when applying seccomp policy

[Takashi Iwai]

On Fri, 17 Aug 2018 05:12:27 +0200,
Hsin-Yu Chao wrote:
> 
> When seccomp policy is applied to filter ioctl syscall with
> SNDRV_CTL_IOCTL_TLV_COMMAND, SNDRV_CTL_IOCTL_TLV_READ and
> SNDRV_CTL_IOCTL_TLV_WRITE in whiltelist, alsa-lib still breaks
> in at snd_ctl_hw_elem_tlv().
> 
> The problem behind is because ioctl() takes unsigned long cmd
> argument, and the signed bit of local int variable could cause
> 0xff bytes appended after casted to unsigned long.
> In kernel, seccomp data struct takes 64 bits argument to check
> against seccomp rules, these unexpected 0xff bytes could make
> the rule check fail.
> 
> Fix the problem by passing unsigned int to ioctl.
> 
> Signed-off-by: Hsin-Yu Chao <hychao at chromium.org>

Thanks, applied now.


Takashi