linux-kernel - [PATCH 3.16 103/136] ALSA: timer: Remove kernel warning at compat ioctl error paths

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Message-ID: <lsq.1518323471.140199901@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "syzbot" <syzkaller@...glegroups.com>,
        "Takashi Iwai" <tiwai@...e.de>
Subject: [PATCH 3.16 103/136] ALSA: timer: Remove kernel warning at compat
 ioctl error paths

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@...e.de>

commit 3d4e8303f2c747c8540a0a0126d0151514f6468b upstream.

Some timer compat ioctls have NULL checks of timer instance with
snd_BUG_ON() that bring up WARN_ON() when the debug option is set.
Actually the condition can be met in the normal situation and it's
confusing and bad to spew kernel warnings with stack trace there.
Let's remove snd_BUG_ON() invocation and replace with the simple
checks.  Also, correct the error code to EBADFD to follow the native
ioctl error handling.

Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/core/timer_compat.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/sound/core/timer_compat.c
+++ b/sound/core/timer_compat.c
@@ -40,11 +40,11 @@ static int snd_timer_user_info_compat(st
 	struct snd_timer *t;
 
 	tu = file->private_data;
-	if (snd_BUG_ON(!tu->timeri))
-		return -ENXIO;
+	if (!tu->timeri)
+		return -EBADFD;
 	t = tu->timeri->timer;
-	if (snd_BUG_ON(!t))
-		return -ENXIO;
+	if (!t)
+		return -EBADFD;
 	memset(&info, 0, sizeof(info));
 	info.card = t->card ? t->card->number : -1;
 	if (t->hw.flags & SNDRV_TIMER_HW_SLAVE)
@@ -73,8 +73,8 @@ static int snd_timer_user_status_compat(
 	struct snd_timer_status32 status;
 	
 	tu = file->private_data;
-	if (snd_BUG_ON(!tu->timeri))
-		return -ENXIO;
+	if (!tu->timeri)
+		return -EBADFD;
 	memset(&status, 0, sizeof(status));
 	status.tstamp.tv_sec = tu->tstamp.tv_sec;
 	status.tstamp.tv_nsec = tu->tstamp.tv_nsec;