linux-kernel - Re: v15-rc1 regression: No sound via usb-audio

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Date:   Mon, 27 Nov 2017 10:59:40 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Jörg Otte <jrg.otte@...il.com>
Cc:     torvalds@...uxfoundation.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: v15-rc1 regression: No sound via usb-audio

On Mon, 27 Nov 2017 09:23:11 +0100,
Jörg Otte wrote:
> 
> With v15-rc1 "alsamixer" has no volume control for usb sound boxes.
> The sound boxes have been working well for years so this a regression.
> 
> Reverting commit:
> 8428a8e: "ALSA: usb-audio: Fix potential zero-division at parsing FU"
> 
> fixes the problem for me completely.

Argh, reading back the changes again, the patch looks really bogus.
Sorry for the mess.

Linus, could you simply revert the one?  I can include it in the next
pull request, but it's likely easier / faster to do it in your side.


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai@...e.de>
Subject: [PATCH] Revert "ALSA: usb-audio: Fix potential zero-division at
 parsing FU"

The commit 8428a8ebde2d ("ALSA: usb-audio: Fix potential zero-division
at parsing FU") is utterly bogus and breaks the case with csize=1
instead of fixing anything.  Just take it back again.

Reported-by: Jörg Otte <jrg.otte@...il.com>
Fixes: 8428a8ebde2d ("ALSA: usb-audio: Fix potential zero-division at parsing FU"
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 sound/usb/mixer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 0537c6322990..61b348383de8 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1476,9 +1476,9 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
 			return -EINVAL;
 		}
 		csize = hdr->bControlSize;
-		if (csize <= 1) {
+		if (!csize) {
 			usb_audio_dbg(state->chip,
-				      "unit %u: invalid bControlSize <= 1\n",
+				      "unit %u: invalid bControlSize == 0\n",
 				      unitid);
 			return -EINVAL;
 		}
-- 
2.15.0