The patch below does not apply to the 4.14-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.

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.159163495... 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;