On Mon, 15 Jun 2020 17:05:11 +0200,
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
>
> The patch below does not apply to the 4.19-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
It should be trivial to adapt this change to older branches.
I'll post it short later.
thanks,
Takashi
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> >From 951e2736f4b11b58dc44d41964fa17c3527d882a Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <mirq-linux@xxxxxxxxxxxx>
> Date: Mon, 8 Jun 2020 18:50:39 +0200
> Subject: [PATCH] ALSA: pcm: disallow linking stream to itself
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> Prevent SNDRV_PCM_IOCTL_LINK linking stream to itself - the code
> can't handle it. Fixed commit is not where bug was introduced, but
> changes the context significantly.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 0888c321de70 ("pcm_native: switch to fdget()/fdput()")
> Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/89c4a2487609a0ed6af3ecf01cc972bdc59a7a2d.1591634956.git.mirq-linux@xxxxxxxxxxxx
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
>
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index c08732998a42..eeab8850ed76 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -2176,6 +2176,12 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
> }
> pcm_file = f.file->private_data;
> substream1 = pcm_file->substream;
> +
> + if (substream == substream1) {
> + res = -EINVAL;
> + goto _badf;
> + }
> +
> group = kzalloc(sizeof(*group), GFP_KERNEL);
> if (!group) {
> res = -ENOMEM;
>
