Message-ID: <CAG_fn=VfLkw5H+e+NPDFeMyE9R7vLN4jnCpe04trGTCcfEuDRA@mail.gmail.com>
Date:   Tue, 8 Oct 2019 11:56:06 +0200
From:   Alexander Potapenko <glider@...gle.com>
To:     Hillf Danton <hdanton@...a.com>
Cc:     syzbot <syzbot+06ddf1788cfd048c5e82@...kaller.appspotmail.com>,
        Hans Verkuil <hverkuil@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>, linux-media@...r.kernel.org,
        mchehab@...nel.org,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: KMSAN: uninit-value in read_sensor_register

On Sat, Jun 8, 2019 at 7:49 AM Hillf Danton <hdanton@...a.com> wrote:
>
>
> Hi
>
> On Fri, 07 Jun 2019 14:53:05 -0700 (PDT) syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    f75e4cfe kmsan: use kmsan_handle_urb() in urb.c
> > git tree:       kmsan
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1454b01ea00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=602468164ccdc30a
> > dashboard link: https://syzkaller.appspot.com/bug?extid=06ddf1788cfd048c5e82
> > compiler:       clang version 9.0.0 (/home/glider/llvm/clang
> > 06d00afa61eef8f7f501ebdb4e8612ea43ec2d78)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12cbead2a00000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1683b761a00000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+06ddf1788cfd048c5e82@...kaller.appspotmail.com
> >
> > usb 1-1: config 0 has an invalid interface number: 110 but max is 0
> > usb 1-1: config 0 has no interface number 0
> > usb 1-1: New USB device found, idVendor=0ac8, idProduct=c301, bcdDevice=
> > 1.4a
> > usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> > usb 1-1: config 0 descriptor??
> > gspca_main: vc032x-2.14.0 probing 0ac8:c301
> > gspca_vc032x: reg_w err -71
> > ==================================================================
> > BUG: KMSAN: uninit-value in read_sensor_register+0x732/0x26a0
> > drivers/media/usb/gspca/vc032x.c:2975
> > CPU: 1 PID: 33 Comm: kworker/1:1 Not tainted 5.1.0+ #1
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Workqueue: usb_hub_wq hub_event
> > Call Trace:
> >   __dump_stack lib/dump_stack.c:77 [inline]
> >   dump_stack+0x191/0x1f0 lib/dump_stack.c:113
> >   kmsan_report+0x130/0x2a0 mm/kmsan/kmsan.c:622
> >   __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:310
> >   read_sensor_register+0x732/0x26a0 drivers/media/usb/gspca/vc032x.c:2975
> >   vc032x_probe_sensor drivers/media/usb/gspca/vc032x.c:3036 [inline]
> >   sd_init+0x2f94/0x5330 drivers/media/usb/gspca/vc032x.c:3167
> >   gspca_dev_probe2+0xee0/0x2240 drivers/media/usb/gspca/gspca.c:1546
> >   gspca_dev_probe+0x346/0x3b0 drivers/media/usb/gspca/gspca.c:1619
> >   sd_probe+0x8d/0xa0 drivers/media/usb/gspca/gl860/gl860.c:523
> >   usb_probe_interface+0xd66/0x1320 drivers/usb/core/driver.c:361
> >   really_probe+0xdae/0x1d80 drivers/base/dd.c:513
> >   driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671
> >   __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778
> >   bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
> >   __device_attach+0x454/0x730 drivers/base/dd.c:844
> >   device_initial_probe+0x4a/0x60 drivers/base/dd.c:891
> >   bus_probe_device+0x137/0x390 drivers/base/bus.c:514
> >   device_add+0x288d/0x30e0 drivers/base/core.c:2106
> >   usb_set_configuration+0x30dc/0x3750 drivers/usb/core/message.c:2027
> >   generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
> >   usb_probe_device+0x14c/0x200 drivers/usb/core/driver.c:266
> >   really_probe+0xdae/0x1d80 drivers/base/dd.c:513
> >   driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671
> >   __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778
> >   bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
> >   __device_attach+0x454/0x730 drivers/base/dd.c:844
> >   device_initial_probe+0x4a/0x60 drivers/base/dd.c:891
> >   bus_probe_device+0x137/0x390 drivers/base/bus.c:514
> >   device_add+0x288d/0x30e0 drivers/base/core.c:2106
> >   usb_new_device+0x23e5/0x2ff0 drivers/usb/core/hub.c:2534
> >   hub_port_connect drivers/usb/core/hub.c:5089 [inline]
> >   hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
> >   port_event drivers/usb/core/hub.c:5350 [inline]
> >   hub_event+0x48d1/0x7290 drivers/usb/core/hub.c:5432
> >   process_one_work+0x1572/0x1f00 kernel/workqueue.c:2269
> >   worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
> >   kthread+0x4b5/0x4f0 kernel/kthread.c:254
> >   ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
> >
> > Uninit was created at:
> >   kmsan_save_stack_with_flags mm/kmsan/kmsan.c:208 [inline]
> >   kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:162
> >   kmsan_kmalloc+0xa4/0x130 mm/kmsan/kmsan_hooks.c:175
> >   kmem_cache_alloc_trace+0x503/0xae0 mm/slub.c:2801
> >   kmalloc include/linux/slab.h:547 [inline]
> >   gspca_dev_probe2+0x30c/0x2240 drivers/media/usb/gspca/gspca.c:1480
> >   gspca_dev_probe+0x346/0x3b0 drivers/media/usb/gspca/gspca.c:1619
> >   sd_probe+0x8d/0xa0 drivers/media/usb/gspca/gl860/gl860.c:523
> >   usb_probe_interface+0xd66/0x1320 drivers/usb/core/driver.c:361
> >   really_probe+0xdae/0x1d80 drivers/base/dd.c:513
> >   driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671
> >   __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778
> >   bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
> >   __device_attach+0x454/0x730 drivers/base/dd.c:844
> >   device_initial_probe+0x4a/0x60 drivers/base/dd.c:891
> >   bus_probe_device+0x137/0x390 drivers/base/bus.c:514
> >   device_add+0x288d/0x30e0 drivers/base/core.c:2106
> >   usb_set_configuration+0x30dc/0x3750 drivers/usb/core/message.c:2027
> >   generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
> >   usb_probe_device+0x14c/0x200 drivers/usb/core/driver.c:266
> >   really_probe+0xdae/0x1d80 drivers/base/dd.c:513
> >   driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671
> >   __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778
> >   bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
> >   __device_attach+0x454/0x730 drivers/base/dd.c:844
> >   device_initial_probe+0x4a/0x60 drivers/base/dd.c:891
> >   bus_probe_device+0x137/0x390 drivers/base/bus.c:514
> >   device_add+0x288d/0x30e0 drivers/base/core.c:2106
> >   usb_new_device+0x23e5/0x2ff0 drivers/usb/core/hub.c:2534
> >   hub_port_connect drivers/usb/core/hub.c:5089 [inline]
> >   hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
> >   port_event drivers/usb/core/hub.c:5350 [inline]
> >   hub_event+0x48d1/0x7290 drivers/usb/core/hub.c:5432
> >   process_one_work+0x1572/0x1f00 kernel/workqueue.c:2269
> >   worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
> >   kthread+0x4b5/0x4f0 kernel/kthread.c:254
> >   ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
> > ==================================================================
> >
> Ignore my noise if you have no interest seeing the syzbot report.
>
> The following tiny diff, made in hope that it may help you perhaps handle
> the report, allocates a slab with zero filled to make the bot happy.
>
> Thanks
> Hillf
> ---
>  drivers/media/usb/gspca.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/gspca.c b/drivers/media/usb/gspca.c
> index be11f78..dcc6ed4 100644
> --- a/drivers/media/usb/gspca.c
> +++ b/drivers/media/usb/gspca.c
> @@ -1468,7 +1468,7 @@ int gspca_dev_probe2(struct usb_interface *intf,
>                 pr_err("couldn't kzalloc gspca struct\n");
>                 return -ENOMEM;
>         }
> -       gspca_dev->usb_buf = kmalloc(USB_BUF_SZ, GFP_KERNEL);
> +       gspca_dev->usb_buf = kmalloc(USB_BUF_SZ, GFP_KERNEL|__GFP_ZERO);
How about calling kzalloc() then?
>         if (!gspca_dev->usb_buf) {
>                 pr_err("out of memory\n");
>                 ret = -ENOMEM;
> --
>
> --
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-- 
Alexander Potapenko
Software Engineer

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