ALSA: pcm: Check PCM state at xfern compat ioctl

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>

diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index 2d957ba635578758172c9d66addc181a3ce438a9..9e7afcb03cd8ee76b22c10eb164acc5fc3caf73e 100644 (file)
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -333,6 +333,8 @@ 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;