From: Johan Hovold johan@kernel.org
commit 0141254b0a74b37aa7eb13d42a56adba84d51c73 upstream.
Make sure to check the return value of usb_altnum_to_altsetting() to avoid dereferencing a NULL pointer when the requested alternate settings is missing.
The format altsetting number may come from a quirk table and there does not seem to be any other validation of it (the corresponding index is checked however).
Fixes: b099b9693d23 ("ALSA: usb-audio: Avoid superfluous usb_set_interface() calls") Cc: stable stable@vger.kernel.org # 4.18 Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20191220093134.1248-1-johan@kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- sound/usb/pcm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 1828225..c022c3e 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -513,9 +513,9 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt) if (WARN_ON(!iface)) return -EINVAL; alts = usb_altnum_to_altsetting(iface, fmt->altsetting); - altsd = get_iface_desc(alts); - if (WARN_ON(altsd->bAlternateSetting != fmt->altsetting)) + if (WARN_ON(!alts)) return -EINVAL; + altsd = get_iface_desc(alts);
if (fmt == subs->cur_audiofmt) return 0;