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

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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 951e2736f4b11b58dc44d41964fa17c3527d882a Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <[email protected]>
Date: Mon, 8 Jun 2020 18:50:39 +0200
Subject: [PATCH] ALSA: pcm: disallow linking stream to itself
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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 [email protected]

Fixes 0888c321de70 ("pcm_native: switch to fdget()/fdput()")

Signed-off-by Michał Mirosław <[email protected]>

Link https://lore.kernel.org/r/89c4a2487609a0ed6af3ecf01cc972bdc59a7a2d.1591634956.git.mirq-linux@rere.qmqm.pl open here

Signed-off-by Takashi Iwai <[email protected]>

sound/core/pcm_native.c +6 -0

index c08732998a42..eeab8850ed76 100644
@@ -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;