From: Michał Mirosław <mirq-li...@rere.qmqm.pl>

commit 951e2736f4b11b58dc44d41964fa17c3527d882a upstream.

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: sta...@vger.kernel.org
Fixes: 0888c321de70 ("pcm_native: switch to fdget()/fdput()")
Signed-off-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
Link: 
https://lore.kernel.org/r/89c4a2487609a0ed6af3ecf01cc972bdc59a7a2d.1591634956.git.mirq-li...@rere.qmqm.pl
Signed-off-by: Takashi Iwai <ti...@suse.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>


---
 sound/core/pcm_native.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1950,6 +1950,11 @@ static int snd_pcm_link(struct snd_pcm_s
        }
        pcm_file = f.file->private_data;
        substream1 = pcm_file->substream;
+       if (substream == substream1) {
+               res = -EINVAL;
+               goto _badf;
+       }
+
        group = kmalloc(sizeof(*group), GFP_KERNEL);
        if (!group) {
                res = -ENOMEM;


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