[PATCH 4.14 035/190] ALSA: pcm: disallow linking stream to itself

Greg Kroah-Hartman
2020-06-19T16:38:03Z

From: Michał Mirosław <mirq-linux@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: 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@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;