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Date: Tue, 6 Sep 2011 15:30:23 +0200 From: Laurent Pinchart <laurent.pinchart@...asonboard.com> To: Hans Verkuil <hverkuil@...all.nl> Cc: Dave Young <hidave.darkstar@...il.com>, Sitsofe Wheeler <sitsofe@...oo.com>, linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, Guennadi Liakhovetski <g.liakhovetski@....de>, Mauro Carvalho Chehab <mchehab@...radead.org> Subject: Re: [PATCH] v4l2: uvcvideo use after free bug fix 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@...oo.com> > > > Signed-off-by: Dave Young <hidave.darkstar@...il.com> > > > Tested-by: Sitsofe Wheeler <sitsofe@...oo.com> > > > Acked-by: Laurent Pinchart <laurent.pinchart@...asonboard.com> > > > > > > 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 >From face69e36b00c0e461a4b894f46213091515defd Mon Sep 17 00:00:00 2001 From: Hans Verkuil <hverkuil@...all.nl> Date: Tue, 6 Sep 2011 15:23:18 +0200 Subject: [PATCH] v4l: Fix use-after-free case in v4l2_device_release Drivers that have no v4l2_device release callback might free the v4l2_device instance in the video_device release callback. Make sure we don't access the v4l2_device instance after it gets freed. Signed-off-by: Laurent Pinchart <laurent.pinchart@...asonboard.com> --- drivers/media/video/v4l2-dev.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index 06f1400..d721565 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -173,6 +173,17 @@ static void v4l2_device_release(struct device *cd) media_device_unregister_entity(&vdev->entity); #endif + /* Do not call v4l2_device_put if there is no release callback set. + * Drivers that have no v4l2_device release callback might free the + * v4l2_dev instance in the video_device release callback below, so we + * must perform this check here. + * + * TODO: In the long run all drivers that use v4l2_device should use the + * v4l2_device release callback. This check will then be unnecessary. + */ + if (v4l2_dev->release == NULL) + v4l2_dev = NULL; + /* Release video_device and perform other cleanups as needed. */ vdev->release(vdev); -- 1.7.3.4 -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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