ALSA: pcm: Check PCM state at xfern compat ioctl

BugLink: http://bugs.launchpad.net/bugs/1778759
commit f13876e2c33a657a71bcbb10f767c0951b165020 upstream.

Since snd_pcm_ioctl_xfern_compat() has no PCM state check, it may go
further and hit the sanity check pcm_sanity_check() when the ioctl is
called right after open.  It may eventually spew a kernel warning, as
triggered by syzbot, depending on kconfig.

The lack of PCM state check there was just an oversight.  Although
it's no real crash, the spurious kernel warning is annoying, so let's
add the proper check.

Reported-by: syzbot+1dac3a4f6bc9c1c675d4@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index 06d7c40af570c05fc20e0d13e1ded5c5ff36823b..6491afbb5fd5704a31a72b2847d4fef2f0001e2f 100644 (file)
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -423,6 +423,8 @@ static int snd_pcm_ioctl_xfern_compat(struct snd_pcm_substream *substream,
                return -ENOTTY;
        if (substream->stream != dir)
                return -EINVAL;
+       if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN)
+               return -EBADFD;
 
        if ((ch = substream->runtime->channels) > 128)
                return -EINVAL;