ALSA: usb-audio: stop parsing UAC2 rates at MAX_NR_RATES

parse_uac2_sample_rate_range() caps the number of enumerated
rates at MAX_NR_RATES, but it only breaks out of the current
rate loop. A malformed UAC2 RANGE response with additional
triplets continues parsing the remaining triplets and repeatedly
prints "invalid uac2 rates" while probe still holds
register_mutex.

Stop the whole parse once the cap is reached and return the
number of rates collected so far.

Fixes: 4fa0e81b8350 ("ALSA: usb-audio: fix possible hang and overflow in parse_uac2_sample_rate_range()")
Cc: stable@vger.kernel.org
Reported-by: syzbot+d56178c27a4710960820@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d56178c27a4710960820
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260415-usb-audio-uac2-rate-cap-v1-1-5ecbafc120d8@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/format.c b/sound/usb/format.c
index 030b4307927a248888cffa63b6e4ca5340485285..4830f9f93ad77e2a9c01589f3e9520e931642925 100644 (file)
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -470,7 +470,7 @@ static int parse_uac2_sample_rate_range(struct snd_usb_audio *chip,
                        nr_rates++;
                        if (nr_rates >= MAX_NR_RATES) {
                                usb_audio_err(chip, "invalid uac2 rates\n");
-                               break;
+                               return nr_rates;
                        }
 
 skip_rate: