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Commit 70986b20 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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ALSA: usb-audio: fix set_format altsetting sanity check 



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: b099b969 ("ALSA: usb-audio: Avoid superfluous usb_set_interface() calls")
Cc: stable <stable@vger.kernel.org>     # 4.18
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191220093134.1248-1-johan@kernel.org


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fb6b1532

sound/usb/pcm.c

+2 −2
Original line number Diff line number Diff line
@@ -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;