Re: FAILED: patch "[PATCH] ALSA: pcm: disallow linking stream to itself" failed to apply to 4.19-stable tree

[Takashi Iwai <tiwai@suse.de>]

On Mon, 15 Jun 2020 17:05:11 +0200,
<gregkh@linuxfoundation.org> 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@vger.kernel.org>.

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@rere.qmqm.pl>
> 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@vger.kernel.org
> Fixes: 0888c321de70 ("pcm_native: switch to fdget()/fdput()")
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> Link: https://lore.kernel.org/r/89c4a2487609a0ed6af3ecf01cc972bdc59a7a2d.1591634956.git.mirq-linux@rere.qmqm.pl
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> 
> 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;
>