[alsa-devel] [PATCH 3/9] ALSA: caiaq: Add a sanity check for invalid EPs

[Takashi Iwai]

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 <andreyknvl at google.com>
Signed-off-by: Takashi Iwai <tiwai at 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;
+	}
+
 	init_waitqueue_head(&cdev->ep1_wait_queue);
 	init_waitqueue_head(&cdev->prepare_wait_queue);
 
-- 
2.14.2