Re: usb/sound/usx2y: WARNING in usb_stream_start

[Takashi Iwai <tiwai@suse.de>]

On Fri, 03 Nov 2017 20:52:49 +0100,
Takashi Iwai wrote:
> 
> On Fri, 03 Nov 2017 15:44:59 +0100,
> Andrey Konovalov wrote:
> > 
> > Hi!
> > 
> > I've got the following report while fuzzing the kernel with syzkaller.
> > 
> > On commit 3a99df9a3d14cd866b5516f8cba515a3bfd554ab (4.14-rc7+).
> > 
> > Looks like there's no check for the actual endpoint types.
> > 
> > usb 1-1: BOGUS urb xfer, pipe 0 != type 3
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 24 at drivers/usb/core/urb.c:471
> > usb_submit_urb+0x113e/0x1400
> > Modules linked in:
> > CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted
> > 4.14.0-rc7-44290-gf28444df2601-dirty #52
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> > Workqueue: usb_hub_wq hub_event
> > task: ffff88006bef5c00 task.stack: ffff88006bf60000
> > RIP: 0010:usb_submit_urb+0x113e/0x1400 drivers/usb/core/urb.c:470
> > RSP: 0018:ffff88006bf67440 EFLAGS: 00010286
> > RAX: 0000000000000029 RBX: ffff880064698c80 RCX: ffffffff812495b5
> > RDX: 0000000000000000 RSI: ffffffff8124d76a RDI: 0000000000000005
> > RBP: ffff88006bf674b0 R08: ffff88006bef5c00 R09: 0000000000000006
> > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> > R13: 0000000000000003 R14: ffff880069a25a20 R15: ffff880064698d04
> > FS:  0000000000000000(0000) GS:ffff88006ca00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007fe6fdba3000 CR3: 0000000068470000 CR4: 00000000000006f0
> > Call Trace:
> >  usb_stream_start+0x48a/0x9f0 sound/usb/usx2y/usb_stream.c:690
> >  us122l_start+0x116/0x290 sound/usb/usx2y/us122l.c:365
> (snip)
> 
> OK, so this looks like another typical issue.
> A totally untested patch is below.  Could you check whether it covers?

FYI, below is the patch with a proper description that I queued to
for-next branch.


Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH] ALSA: usx2y: Fix invalid stream URBs

The us122l driver creates URBs per the fixed endpoints, and this may
end up with URBs with inconsistent pipes when a fuzzer or a malicious
program deals with the manipulated endpoints.  It ends up with a
kernel warning like:

  usb 1-1: BOGUS urb xfer, pipe 0 != type 3
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 24 at drivers/usb/core/urb.c:471
  usb_submit_urb+0x113e/0x1400
  Call Trace:
   usb_stream_start+0x48a/0x9f0 sound/usb/usx2y/usb_stream.c:690
   us122l_start+0x116/0x290 sound/usb/usx2y/us122l.c:365
   us122l_create_card sound/usb/usx2y/us122l.c:502
   us122l_usb_probe sound/usb/usx2y/us122l.c:588
   ....

For avoiding the bad access, this patch adds a few sanity checks of
the validity of created URBs like previous similar fixes using the new
usb_urb_ep_type_check() helper function.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/usb/usx2y/usb_stream.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/sound/usb/usx2y/usb_stream.c b/sound/usb/usx2y/usb_stream.c
index e229abd21652..b0f8979ff2d2 100644
--- a/sound/usb/usx2y/usb_stream.c
+++ b/sound/usb/usx2y/usb_stream.c
@@ -56,7 +56,7 @@ static void playback_prep_freqn(struct usb_stream_kernel *sk, struct urb *urb)
 		    lb, s->period_size);
 }
 
-static void init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
+static int init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
 			   struct urb **urbs, char *transfer,
 			   struct usb_device *dev, int pipe)
 {
@@ -77,6 +77,8 @@ static void init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
 		urb->interval = 1;
 		if (usb_pipeout(pipe))
 			continue;
+		if (usb_urb_ep_type_check(urb))
+			return -EINVAL;
 
 		urb->transfer_buffer_length = transfer_length;
 		desc = urb->iso_frame_desc;
@@ -87,9 +89,11 @@ static void init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
 			desc[p].length = maxpacket;
 		}
 	}
+
+	return 0;
 }
 
-static void init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
+static int init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
 		      struct usb_device *dev, int in_pipe, int out_pipe)
 {
 	struct usb_stream	*s = sk->s;
@@ -103,9 +107,12 @@ static void init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
 		sk->outurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
 	}
 
-	init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe);
-	init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
-		       out_pipe);
+	if (init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe) ||
+	    init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
+			   out_pipe))
+		return -EINVAL;
+
+	return 0;
 }
 
 
@@ -226,7 +233,11 @@ struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
 	else
 		sk->freqn = get_usb_high_speed_rate(sample_rate);
 
-	init_urbs(sk, use_packsize, dev, in_pipe, out_pipe);
+	if (init_urbs(sk, use_packsize, dev, in_pipe, out_pipe) < 0) {
+		usb_stream_free(sk);
+		return NULL;
+	}
+
 	sk->s->state = usb_stream_stopped;
 out:
 	return sk->s;
-- 
2.14.3