On Wed, 11 Oct 2017 16:20:31 +0200,
Johan Hovold wrote:
>
> On Wed, Oct 11, 2017 at 12:36:40PM +0200, Takashi Iwai wrote:
> > As syzkaller spotted, currently caiaq driver submits a URB with the
> > fixed EP without checking whether it's actually available, which may
> > result in a kernel warning like:
> > usb 1-1: BOGUS urb xfer, pipe 3 != type 1
> > ------------[ cut here ]------------
> > WARNING: CPU: 1 PID: 1150 at drivers/usb/core/urb.c:449
> > usb_submit_urb+0xf8a/0x11d0
> > Modules linked in:
> > CPU: 1 PID: 1150 Comm: kworker/1:1 Not tainted
> > 4.14.0-rc2-42660-g24b7bd59eec0 #277
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
> > 01/01/2011
> > Workqueue: usb_hub_wq hub_event
> > Call Trace:
> > init_card sound/usb/caiaq/device.c:467
> > snd_probe+0x81c/0x1150 sound/usb/caiaq/device.c:525
> > usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
> > ....
> >
> > This patch adds a sanity check of validity of EPs at the device
> > initialization phase for avoiding the call with an invalid EP.
> >
> > Reported-by: Andrey Konovalov <andreyk...@google.com>
> > Tested-by: Andrey Konovalov <andreyk...@google.com>
> > Signed-off-by: Takashi Iwai <ti...@suse.de>
> > ---
> > sound/usb/caiaq/device.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c
> > index 0fb6b1b79261..a29674bf96e5 100644
> > --- a/sound/usb/caiaq/device.c
> > +++ b/sound/usb/caiaq/device.c
> > @@ -461,6 +461,13 @@ static int init_card(struct snd_usb_caiaqdev *cdev)
> > cdev->midi_out_buf, EP1_BUFSIZE,
> > snd_usb_caiaq_midi_output_done, cdev);
> >
> > + /* sanity checks of EPs before actually submitting */
> > + if (usb_urb_ep_type_check(&cdev->ep1_in_urb) ||
> > + usb_urb_ep_type_check(&cdev->midi_out_urb)) {
> > + dev_err(dev, "invalid EPs\n");
> > + return -EINVAL;
> > + }
> > +
>
> Unrelated to this patch, but this driver fails to kill the ep1_in_urb
> (which is submitted in this function) in case of later probe errors.
> This can lead to use-after-free or crashes in the completion callback.
Yes, a good catch. Below is the fix patch.
thanks,
Takashi
-- 8< --
From: Takashi Iwai <ti...@suse.de>
Subject: [PATCH] ALSA: caiaq: Fix stray URB at probe error path
caiaq driver doesn't kill the URB properly at its error path during
the probe, which may lead to a use-after-free error later. This patch
addresses it.
Reported-by: Johan Hovold <jo...@kernel.org>
Signed-off-by: Takashi Iwai <ti...@suse.de>
---
sound/usb/caiaq/device.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c
index a29674bf96e5..d55ca48de3ea 100644
--- a/sound/usb/caiaq/device.c
+++ b/sound/usb/caiaq/device.c
@@ -476,10 +476,12 @@ static int init_card(struct snd_usb_caiaqdev *cdev)
err = snd_usb_caiaq_send_command(cdev, EP1_CMD_GET_DEVICE_INFO, NULL,
0);
if (err)
- return err;
+ goto err_kill_urb;
- if (!wait_event_timeout(cdev->ep1_wait_queue, cdev->spec_received, HZ))
- return -ENODEV;
+ if (!wait_event_timeout(cdev->ep1_wait_queue, cdev->spec_received, HZ))
{
+ err = -ENODEV;
+ goto err_kill_urb;
+ }
usb_string(usb_dev, usb_dev->descriptor.iManufacturer,
cdev->vendor_name, CAIAQ_USB_STR_LEN);
@@ -514,6 +516,10 @@ static int init_card(struct snd_usb_caiaqdev *cdev)
setup_card(cdev);
return 0;
+
+ err_kill_urb:
+ usb_kill_urb(&cdev->ep1_in_urb);
+ return err;
}
static int snd_probe(struct usb_interface *intf,
--
2.14.2
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