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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Johan Carlsson <johan.carlsson@teenage.engineering>,
	Takashi Iwai <tiwai@suse.de>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 128/148] ALSA: usb-audio: Stop parsing channels bits when all channels are found.
Date: Sun, 24 Mar 2024 19:49:52 -0400
Message-ID: <20240324235012.1356413-129-sashal@kernel.org>
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From: Johan Carlsson <johan.carlsson@teenage.engineering>

[ 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>
---
 sound/usb/stream.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 1cfb30465df7d..3f20438a1b56e 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -306,9 +306,12 @@ 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 */
-- 
2.43.0