On Tue, Sep 12, 2017 at 12:46 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
> On Mon, 11 Sep 2017 13:17:39 +0200,
> Andrey Konovalov wrote:
>>
>> On Tue, Sep 5, 2017 at 6:08 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
>> > On Tue, 05 Sep 2017 13:12:14 +0200,
>> > Andrey Konovalov wrote:
>> >>
>> >> Hi!
>> >>
>> >> While working on adding USB fuzzing support to syzkaller, I got the
>> >> following crash.
>> >>
>> >> On commit 81a84ad3cb5711cec79f4dd53a4ce026b092c432 (4.13+).
>> >>
>> >> My .config is attached. I don't have a reproducer for this bug.
>> >>
>> >> ==================================================================
>> >> BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70
>> >> sound/core/rawmidi.c:1617
>> >> Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
>> >>
>> >> CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29
>> >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>> >> Workqueue: events autoload_drivers
>> >> Call Trace:
>> >> __dump_stack lib/dump_stack.c:16 [inline]
>> >> dump_stack+0x192/0x22c lib/dump_stack.c:52
>> >> print_address_description+0x78/0x280 mm/kasan/report.c:252
>> >> kasan_report_error mm/kasan/report.c:351 [inline]
>> >> kasan_report+0x230/0x340 mm/kasan/report.c:409
>> >> __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435
>> >> snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617
>> >> snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192
>> >> device_release+0x13f/0x210 drivers/base/core.c:814
>> >> kobject_cleanup lib/kobject.c:648 [inline]
>> >> kobject_release lib/kobject.c:677 [inline]
>> >> kref_put include/linux/kref.h:70 [inline]
>> >> kobject_put+0x145/0x240 lib/kobject.c:694
>> >> put_device+0x25/0x30 drivers/base/core.c:1799
>> >> klist_devices_put+0x36/0x40 drivers/base/bus.c:827
>> >> klist_next+0x264/0x4a0 lib/klist.c:403
>> >> next_device drivers/base/bus.c:270 [inline]
>> >> bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312
>> >> autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117
>> >> process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097
>> >> worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231
>> >> kthread+0x324/0x3f0 kernel/kthread.c:231
>> >> ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
>> >
>> > So this looks like a pending work triggering the issue when performed
>> > during the card free. What about the patch below as a quick band-aid
>> > fix?
>> >
>> >
>> > thanks,
>> >
>> > Takashi
>>
>> Hi Takashi,
>>
>> I've been running syzkaller with your patch for a few days and didn't
>> see any more of those reports.
>>
>> Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
>
> Thanks, I merged the fix now.
> FWIW, below is the official patch I merged.
Great, thanks!
>
>
> Takashi
>
> -- 8< --
> From: Takashi Iwai <tiwai@xxxxxxx>
> Subject: [PATCH] ALSA: seq: Cancel pending autoload work at unbinding device
>
> ALSA sequencer core has a mechanism to load the enumerated devices
> automatically, and it's performed in an off-load work. This seems
> causing some race when a sequencer is removed while the pending
> autoload work is running. As syzkaller spotted, it may lead to some
> use-after-free:
> BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70
> sound/core/rawmidi.c:1617
> Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
>
> CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Workqueue: events autoload_drivers
> Call Trace:
> __dump_stack lib/dump_stack.c:16 [inline]
> dump_stack+0x192/0x22c lib/dump_stack.c:52
> print_address_description+0x78/0x280 mm/kasan/report.c:252
> kasan_report_error mm/kasan/report.c:351 [inline]
> kasan_report+0x230/0x340 mm/kasan/report.c:409
> __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435
> snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617
> snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192
> device_release+0x13f/0x210 drivers/base/core.c:814
> kobject_cleanup lib/kobject.c:648 [inline]
> kobject_release lib/kobject.c:677 [inline]
> kref_put include/linux/kref.h:70 [inline]
> kobject_put+0x145/0x240 lib/kobject.c:694
> put_device+0x25/0x30 drivers/base/core.c:1799
> klist_devices_put+0x36/0x40 drivers/base/bus.c:827
> klist_next+0x264/0x4a0 lib/klist.c:403
> next_device drivers/base/bus.c:270 [inline]
> bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312
> autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117
> process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097
> worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231
> kthread+0x324/0x3f0 kernel/kthread.c:231
> ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
>
> The fix is simply to assure canceling the autoload work at removing
> the device.
>
> Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> ---
> sound/core/seq_device.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/sound/core/seq_device.c b/sound/core/seq_device.c
> index c4acf17e9f5e..e40a2cba5002 100644
> --- a/sound/core/seq_device.c
> +++ b/sound/core/seq_device.c
> @@ -148,8 +148,10 @@ void snd_seq_device_load_drivers(void)
> flush_work(&autoload_work);
> }
> EXPORT_SYMBOL(snd_seq_device_load_drivers);
> +#define cancel_autoload_drivers() cancel_work_sync(&autoload_work)
> #else
> #define queue_autoload_drivers() /* NOP */
> +#define cancel_autoload_drivers() /* NOP */
> #endif
>
> /*
> @@ -159,6 +161,7 @@ static int snd_seq_device_dev_free(struct snd_device *device)
> {
> struct snd_seq_device *dev = device->device_data;
>
> + cancel_autoload_drivers();
> put_device(&dev->dev);
> return 0;
> }
> --
> 2.14.1
>
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
