Commit 0141254b authored Dec 20, 2019 by Johan Hovold Committed by Takashi Iwai Dec 20, 2019

ALSA: usb-audio: fix set_format altsetting sanity check



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: b099b969 ("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>

parent 66c5d718

sound/usb/pcm.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -506,9 +506,9 @@ 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 && !subs->need_setup_fmt)
		return 0;

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