From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-21.sinamail.sina.com.cn (r3-21.sinamail.sina.com.cn [202.108.3.21]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 769FC407CCC for ; Thu, 3 Sep 2026 09:41:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.21 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788428511; cv=none; b=OnvVnIQ39ghMnNh+c0pl8Q7OpnP6qePJNK3Y/g0XL+FfdsvKsKqjOocK9v60ljN0Umj14+SkEb4QTHVSzWXYvb0f1cEh8xGhmuj822ljOVh2nMTsQ157Q7FILzZctXqw7JUspKhCBaEwz+EosuGIR1o5s3ddtQh+LCrawd9okRY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788428511; c=relaxed/simple; bh=w7XT7tqdRJHJv6GTPxTS9/YfRW4PTAdV3z6v+WeD4Oc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hA4iX5TtszrjhqwhoGdcDq8aWZjafH57SpWGwHNTzy5MQPvXRqMUM1nsil0YD/3LbA32geAqQaW1uK9xU9HRvRyYWcEMWpQ+GhUNWOCt5CErkjVchNgRG8gvGN6UMdEaJKnWOirlT2kPrIGnq1T1uxRrTAItoW5aw1Vc6DBZ9bk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=JdPYteTV; arc=none smtp.client-ip=202.108.3.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="JdPYteTV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1788428508; bh=DOnK4Nx9hl6+FcBbSwW7N2dxLUjgJ/U24pl5jA6Knxg=; h=From:Subject:Date:Message-ID; b=JdPYteTVwd/7uEVmqTzPtqjmYFHCUlFb1mYQzi2JN4wlsrbrjMAUQxK0kVYEAMB/v wwYCVTinvNyXzKlsrrV7GijtY526SWa1PlcdGPqdcECVdN7uXFffz9QX58a5jrx+fp ceH+4VSZngNJwzZCJHn7p0Vv9ACUXAL6umWlqRNE= X-SMAIL-HELO: lxu-ped-host.. Received: from unknown (HELO lxu-ped-host..)([111.198.231.89]) by sina.com (10.54.253.33) with ESMTP id 6A9940B100007805; Thu, 3 Sep 2026 17:41:08 +0800 (CST) X-Sender: eadavis@sina.com X-Auth-ID: eadavis@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=eadavis@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=eadavis@sina.com X-SMAIL-MID: 3288806685154 X-SMAIL-UIID: 6A6E91488387490C837E6E45F8C07570-20260903-174108-1 From: Edward Adam Davis To: tiwai@suse.de Cc: daniel@caiaq.org, eadavis@sina.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, linux-usb@vger.kernel.org, perex@perex.cz, syzbot+832ce9fa3face1b7d44d@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, tiwai@suse.com, zonque@gmail.com Subject: Re: [PATCH] ALSA: caiaq: Decoupling ep1_in_urb in caiaq dev Date: Thu, 3 Sep 2026 17:41:05 +0800 Message-ID: <20260903094105.539519-1-eadavis@sina.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <87pkyu8yu1.wl-tiwai@suse.de> References: <87pkyu8yu1.wl-tiwai@suse.de> Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Edward Aadm Davis On Thu, 03 Sep 2026 11:32:22 +0200, Takashi Iwai wrote: > > The epq_in_urb object belonging to the caiaq device is coupled within > > the struct snd_usb_caiaqdev. After usb_submit_urb(epq_in_urb, GFP_KERNEL) > > executes successfully, epq_in_urb is successfully added to the urbp_list > > queue of the dummy HCD driver (userspace specifies dummy_hcd as the HCD > > layer driver for the caiaq USB device). > > > > When init_card() calls snd_usb_caiaq_send_command() which subsequently > > fails due to a timeout, and proceeds to call snd_card_free() to release > > the card, the embedded ep1_in_urb object is also freed. When the dummy > > HCD driver detects that the URB has been unlinked, it returns the URB > > (by usb_hcd_giveback_urb()), which triggers [1]. > > > > Decouple the ep1_in_urb object from the struct snd_usb_caiaqdev and switch > > to using a pointer instead. Separately allocate and manage the memory for > > ep1_in_urb to prevent the release of the snd_card memory object from > > interfering with it. > > > > [1] > > BUG: KASAN: slab-use-after-free in usb_free_urb+0x24/0x120 drivers/usb/core/urb.c:96 > > Write of size 4 at addr ffff88803cee1050 by task ktimers/1/29 > > Call Trace: > > usb_free_urb+0x24/0x120 drivers/usb/core/urb.c:96 > > dummy_timer+0xaac/0x4d50 drivers/usb/gadget/udc/dummy_hcd.c:2019 > > __run_hrtimer kernel/time/hrtimer.c:2067 [inline] > > __hrtimer_run_queues+0x3eb/0xaf0 kernel/time/hrtimer.c:2124 > > hrtimer_run_softirq+0x1e1/0x2e0 kernel/time/hrtimer.c:2141 > > > > Allocated by task 36: > > snd_card_new+0x7b/0x110 sound/core/init.c:184 > > create_card sound/usb/caiaq/device.c:429 [inline] > > snd_probe+0x236/0x1af0 sound/usb/caiaq/device.c:544 > > > > Freed by task 36: > > snd_card_free_when_closed sound/core/init.c:630 [inline] > > snd_card_free+0x138/0x1d0 sound/core/init.c:662 > > snd_probe+0x162b/0x1af0 sound/usb/caiaq/device.c:553 > > > > Reported-by: syzbot+832ce9fa3face1b7d44d@syzkaller.appspotmail.com > > Fixes: 523f1dce3743 ("[ALSA] Add Native Instrument usb audio device support") > > Closes: https://syzkaller.appspot.com/bug?extid=832ce9fa3face1b7d44d > > Tested-by: syzbot+832ce9fa3face1b7d44d@syzkaller.appspotmail.com > > Signed-off-by: Edward Adam Davis > > --- > > sound/usb/caiaq/device.c | 19 +++++++++++-------- > > sound/usb/caiaq/device.h | 2 +- > > 2 files changed, 12 insertions(+), 9 deletions(-) > > > > diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c > > index a16e59248480..138b58914f1c 100644 > > --- a/sound/usb/caiaq/device.c > > +++ b/sound/usb/caiaq/device.c > > @@ -192,8 +192,8 @@ static void usb_ep1_command_reply_dispatch (struct urb* urb) > > break; > > } > > > > - cdev->ep1_in_urb.actual_length = 0; > > - ret = usb_submit_urb(&cdev->ep1_in_urb, GFP_ATOMIC); > > + cdev->ep1_in_urb->actual_length = 0; > > + ret = usb_submit_urb(cdev->ep1_in_urb, GFP_ATOMIC); > > if (ret < 0) > > dev_err(dev, "unable to submit urb. OOM!?\n"); > > } > > @@ -408,6 +408,8 @@ static void card_free(struct snd_card *card) > > #endif > > snd_usb_caiaq_audio_free(cdev); > > usb_put_dev(cdev->chip.dev); > > + usb_free_urb(cdev->ep1_in_urb); > > + cdev->ep1_in_urb = NULL; > > } > > > > static int create_card(struct usb_device *usb_dev, > > @@ -457,10 +459,11 @@ static int init_card(struct snd_usb_caiaqdev *cdev) > > return -EIO; > > } > > > > - usb_init_urb(&cdev->ep1_in_urb); > > + cdev->ep1_in_urb = usb_alloc_urb(0, GFP_KERNEL); > > + usb_init_urb(cdev->ep1_in_urb); > > The error check is missing here, as sashiko review pointed out. > Could you fix and resubmit? OK. I will fix and resubmit. > > (The other issues reported there -- the potential-double-free and the > midi_out_urb handling can be skipped here; I'll fix those > individually.) I can handle `midi_out_urb` as well. BR, Edward