From: Takashi Iwai Date: Thu, 10 Jan 2013 13:06:38 +0000 (+0100) Subject: ALSA: usb-audio: Fix NULL dereference by access to non-existing substream X-Git-Tag: v3.8-rc4~8^2~6 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=31be5425d795585251a3ee970319c37643e0cda2;p=platform%2Fkernel%2Flinux-stable.git ALSA: usb-audio: Fix NULL dereference by access to non-existing substream The commit [0d9741c0: ALSA: usb-audio: sync ep init fix for audioformat mismatch] introduced the correction of parameters to be set for sync EP. But since the new code assumes that the sync EP is always paired with the data EP of another direction, it triggers Oops when a device only with a single direction is used. This patch adds a proper check of sync EP type and the presence of the paired substream for avoiding the crash. Reported-and-tested-by: Jens Axboe Signed-off-by: Takashi Iwai --- diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index c659310..d82e378 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -511,6 +511,16 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs) struct snd_usb_substream *sync_subs = &subs->stream->substream[subs->direction ^ 1]; + if (subs->sync_endpoint->type != SND_USB_ENDPOINT_TYPE_DATA || + !subs->stream) + return snd_usb_endpoint_set_params(subs->sync_endpoint, + subs->pcm_format, + subs->channels, + subs->period_bytes, + subs->cur_rate, + subs->cur_audiofmt, + NULL); + /* Try to find the best matching audioformat. */ list_for_each_entry(fp, &sync_subs->fmt_list, list) { int score = match_endpoint_audioformats(fp, subs->cur_audiofmt,