Re: [PATCH] v4l2: uvcvideo use after free bug fix

[Laurent Pinchart]

Hi,

On Tuesday 06 September 2011 15:02:54 Hans Verkuil wrote:
> On Tuesday, September 06, 2011 14:12:14 Laurent Pinchart wrote:
> > On Tuesday 06 September 2011 14:08:08 Dave Young wrote:
> > > Reported-by: Sitsofe Wheeler <sitsofe@xxxxxxxxx>
> > > Signed-off-by: Dave Young <hidave.darkstar@xxxxxxxxx>
> > > Tested-by: Sitsofe Wheeler <sitsofe@xxxxxxxxx>
> > > Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > 
> > > Unplugging uvc video camera trigger following oops:
> > > 
> > > eeepc kernel: [ 1393.500719] usb 3-2: USB disconnect, device number 4
> > > eeepc kernel: [ 1393.504351] uvcvideo: Failed to resubmit video URB
> > > (-19). eeepc kernel: [ 1495.428853] BUG: unable to handle kernel
> > > paging request at 6b6b6bcb eeepc kernel: [ 1495.429017] IP:
> > > [<b0358d37>]
> > > dev_get_drvdata+0x17/0x20 eeepc kernel: [ 1495.429017] *pde = 00000000
> > > eeepc kernel: [ 1495.429017] Oops: 0000 [#1] DEBUG_PAGEALLOC
> > > eeepc kernel: [ 1495.429017]
> > > eeepc kernel: [ 1495.429017] Pid: 3476, comm: cheese Not tainted
> > > 3.1.0-rc3-00270-g7a54f5e-dirty #485 ASUSTeK Computer INC. 900/900 eeepc
> > > kernel: [ 1495.429017] EIP: 0060:[<b0358d37>] EFLAGS: 00010202 CPU: 0
> > > eeepc kernel: [ 1495.429017] EIP is at dev_get_drvdata+0x17/0x20
> > > eeepc kernel: [ 1495.429017] EAX: 6b6b6b6b EBX: eb08d870 ECX: 00000000
> > > EDX: eb08d930 eeepc kernel: [ 1495.429017] ESI: eb08d870 EDI: eb08d870
> > > EBP: d3249cac ESP: d3249cac eeepc kernel: [ 1495.429017]  DS: 007b ES:
> > > 007b FS: 0000 GS: 00e0 SS: 0068 eeepc kernel: [ 1495.429017] Process
> > > cheese (pid: 3476, ti=d3248000 task=df46d870 task.ti=d3248000) eeepc
> > > kernel: [ 1495.429017] Stack:
> > > eeepc kernel: [ 1495.429017]  d3249cb8 b03e77a1 d307b840 d3249ccc
> > > b03e77d1 d307b840 eb08d870 eb08d830 eeepc kernel: [ 1495.429017] 
> > > d3249ce4 b03ed3b7 00000246 d307b840 eb08d870 d3021b80 d3249cec
> > > b03ed565 eeepc kernel: [ 1495.429017]  d3249cfc b03e044d e8323d10
> > > b06e013c d3249d18 b0355fb9 fffffffe d3249d1c eeepc kernel: [
> > > 1495.429017] Call Trace:
> > > eeepc kernel: [ 1495.429017]  [<b03e77a1>]
> > > v4l2_device_disconnect+0x11/0x30 eeepc kernel: [ 1495.429017] 
> > > [<b03e77d1>] v4l2_device_unregister+0x11/0x50 eeepc kernel: [
> > > 1495.429017]  [<b03ed3b7>] uvc_delete+0x37/0x110 eeepc kernel: [
> > > 1495.429017]  [<b03ed565>] uvc_release+0x25/0x30 eeepc kernel: [
> > > 1495.429017]  [<b03e044d>] v4l2_device_release+0x9d/0xc0 eeepc kernel:
> > > [ 1495.429017]  [<b0355fb9>] device_release+0x19/0x90 eeepc kernel: [
> > > 1495.429017]  [<b03adfdc>] ? usb_hcd_unlink_urb+0x7c/0x90 eeepc
> > > kernel: [ 1495.429017]  [<b026b99c>] kobject_release+0x3c/0x90 eeepc
> > > kernel: [ 1495.429017]  [<b026b960>] ? kobject_del+0x30/0x30 eeepc
> > > kernel: [ 1495.429017]  [<b026ca4c>] kref_put+0x2c/0x60
> > > eeepc kernel: [ 1495.429017]  [<b026b88d>] kobject_put+0x1d/0x50
> > > eeepc kernel: [ 1495.429017]  [<b03b2385>] ?
> > > usb_autopm_put_interface+0x25/0x30 eeepc kernel: [ 1495.429017]
> > > [<b03f0e5d>] ? uvc_v4l2_release+0x5d/0xd0 eeepc kernel: [ 1495.429017]
> > > [<b0355d2f>] put_device+0xf/0x20
> > > eeepc kernel: [ 1495.429017]  [<b03dfa96>] v4l2_release+0x56/0x60
> > > eeepc kernel: [ 1495.429017]  [<b019c8dc>] fput+0xcc/0x220
> > > eeepc kernel: [ 1495.429017]  [<b01990f4>] filp_close+0x44/0x70
> > > eeepc kernel: [ 1495.429017]  [<b012b238>] put_files_struct+0x158/0x180
> > > eeepc kernel: [ 1495.429017]  [<b012b100>] ?
> > > put_files_struct+0x20/0x180 eeepc kernel: [ 1495.429017]  [<b012b2a0>]
> > > exit_files+0x40/0x50 eeepc kernel: [ 1495.429017]  [<b012b9e7>]
> > > do_exit+0x5a7/0x660 eeepc kernel: [ 1495.429017]  [<b0135f72>] ?
> > > __dequeue_signal+0x12/0x120 eeepc kernel: [ 1495.429017]  [<b055edf2>]
> > > ? _raw_spin_unlock_irq+0x22/0x30 eeepc kernel: [ 1495.429017] 
> > > [<b012badc>] do_group_exit+0x3c/0xb0 eeepc kernel: [ 1495.429017] 
> > > [<b015792b>] ? trace_hardirqs_on+0xb/0x10 eeepc kernel: [ 1495.429017]
> > >  [<b013755f>]
> > > get_signal_to_deliver+0x18f/0x570 eeepc kernel: [ 1495.429017]
> > > [<b01020f7>] do_signal+0x47/0x9e0
> > > eeepc kernel: [ 1495.429017]  [<b055edf2>] ?
> > > _raw_spin_unlock_irq+0x22/0x30 eeepc kernel: [ 1495.429017] 
> > > [<b015792b>] ? trace_hardirqs_on+0xb/0x10 eeepc kernel: [ 1495.429017]
> > >  [<b0123300>] ? T.1034+0x30/0xc0
> > > eeepc kernel: [ 1495.429017]  [<b055c45f>] ? schedule+0x29f/0x640
> > > eeepc kernel: [ 1495.429017]  [<b0102ac8>] do_notify_resume+0x38/0x40
> > > eeepc kernel: [ 1495.429017]  [<b055f154>] work_notifysig+0x9/0x11
> > > eeepc kernel: [ 1495.429017] Code: e5 5d 83 f8 01 19 c0 f7 d0 83 e0 f0
> > > c3 8d b4 26 00 00 00 00 55 85 c0 89 e5 75 09 31 c0 5d c3 90 8d 74 26
> > > 00 8b 40 04 85 c0 74 f0 <8b> 40 60 5d c3 8d 74 26 00 55 89 e5 53 89 c3
> > > 83 ec 04 8b 40 04 eeepc kernel: [ 1495.429017] EIP: [<b0358d37>]
> > > dev_get_drvdata+0x17/0x20 SS:ESP 0068:d3249cac eeepc kernel: [
> > > 1495.429017] CR2: 000000006b6b6bcb
> > > eeepc kernel: [ 1495.466975] uvcvideo: Failed to resubmit video URB
> > > (-27). eeepc kernel: [ 1495.467860] uvcvideo: Failed to resubmit video
> > > URB (-27). eeepc kernel: last message repeated 3 times
> > > eeepc kernel: [ 1495.512610] ---[ end trace 73ec16848794e5a5 ]---
> > > 
> > > For uvc device, dev->vdev.dev is the &intf->dev,
> > > 
> > > uvc_delete code is as below:
> > > 	usb_put_intf(dev->intf);
> > > 	usb_put_dev(dev->udev);
> > > 	
> > > 	uvc_status_cleanup(dev);
> > > 	uvc_ctrl_cleanup_device(dev);
> > > 
> > > ## the intf dev is released above, so below code will oops.
> > > 
> > > 	if (dev->vdev.dev)
> > > 	
> > > 		v4l2_device_unregister(&dev->vdev);
> > > 
> > > Fix it by get_device in v4l2_device_register and put_device in
> > > v4l2_device_disconnect ---
> > > 
> > >  drivers/media/video/v4l2-device.c |    2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/drivers/media/video/v4l2-device.c
> > > b/drivers/media/video/v4l2-device.c index c72856c..e6a2c3b 100644
> > > --- a/drivers/media/video/v4l2-device.c
> > > +++ b/drivers/media/video/v4l2-device.c
> > > @@ -38,6 +38,7 @@ int v4l2_device_register(struct device *dev, struct
> > > v4l2_device *v4l2_dev) mutex_init(&v4l2_dev->ioctl_lock);
> > > 
> > >  	v4l2_prio_init(&v4l2_dev->prio);
> > >  	kref_init(&v4l2_dev->ref);
> > > 
> > > +	get_device(dev);
> > > 
> > >  	v4l2_dev->dev = dev;
> > 
> > We store a reference to the device in v4l2_dev, and we use it later. We
> > thus need either get a reference to the device (like done by this
> > patch), or mandate drivers not to release their reference to the device
> > before calling v4l2_device_unregister and/or v4l2_device_disconnect (in
> > this case that would mean moving the usb_put_intf call after the
> > v4l2_device_unregister call in the uvcvideo driver).
> > 
> > Do you have a preference ?
> 
> My preference would be to get a reference ourselves,

Sounds good to me.

> but I don't have the time to fully analyze this. So I leave that to you.

I will pick the patch and push it to v3.1. Dave, your patch fixes a problem 
that is not UVC-specific. Do you mind if I rephrase the (pretty verbose) 
commit message to explain the v4l issue instead ?

Hans, can I get your SoB line for