From: Johan Carlsson <johan.carlsson@teenage.engineering>
Date: Wed, 13 Mar 2024 08:15:09 +0000 (+0100)
Subject: ALSA: usb-audio: Stop parsing channels bits when all channels are found.
X-Git-Tag: v6.8.2~164
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6d88b289fb0a8d055cb79d1c46a56aba7809d96d;p=thirdparty%2Fkernel%2Fstable.git

ALSA: usb-audio: Stop parsing channels bits when all channels are found.

[ Upstream commit a39d51ff1f52cd0b6fe7d379ac93bd8b4237d1b7 ]

If a usb audio device sets more bits than the amount of channels
it could write outside of the map array.

Signed-off-by: Johan Carlsson <johan.carlsson@teenage.engineering>
Fixes: 04324ccc75f9 ("ALSA: usb-audio: add channel map support")
Message-ID: <20240313081509.9801-1-johan.carlsson@teenage.engineering>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 3d4add94e367d..d5409f3879455 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -300,9 +300,12 @@ static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits,
 	c = 0;
 
 	if (bits) {
-		for (; bits && *maps; maps++, bits >>= 1)
+		for (; bits && *maps; maps++, bits >>= 1) {
 			if (bits & 1)
 				chmap->map[c++] = *maps;
+			if (c == chmap->channels)
+				break;
+		}
 	} else {
 		/* If we're missing wChannelConfig, then guess something
 		    to make sure the channel map is not skipped entirely */