[PATCH 5.10.y] ALSA: pcm: Properly take rwsem lock in ctl_elem_read_user/ctl_elem_write_user to prevent UAF

[Greg KH]

On Fri, Jan 13, 2023 at 03:26:39PM +0100, Takashi Iwai wrote:
> From: Clement Lecigne <clecigne at google.com>
> 
> [ Note: this is a fix that works around the bug equivalently as the
>   two upstream commits:
>    1fa4445f9adf ("ALSA: control - introduce snd_ctl_notify_one() helper")
>    56b88b50565c ("ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF")
>   but in a simpler way to fit with older stable trees -- tiwai ]

Thanks for the backport, now queued up.

greg k-h