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* possible deadlock in usb_deregister_dev
@ 2019-08-05 11:58 syzbot
  2019-08-06 14:22 ` Oliver Neukum
  2019-08-09 18:18 ` syzbot
  0 siblings, 2 replies; 7+ messages in thread
From: syzbot @ 2019-08-05 11:58 UTC (permalink / raw)
  To: andreyknvl, gregkh, linux-kernel, linux-usb, syzkaller-bugs

Hello,

syzbot found the following crash on:

HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=13b5bc8a600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=792eb47789f57810
dashboard link: https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com

usb 4-1: USB disconnect, device number 85
======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc2+ #24 Not tainted
------------------------------------------------------
kworker/0:2/105 is trying to acquire lock:
000000003db0b025 (minor_rwsem){++++}, at: usb_deregister_dev  
drivers/usb/core/file.c:238 [inline]
000000003db0b025 (minor_rwsem){++++}, at: usb_deregister_dev+0x61/0x270  
drivers/usb/core/file.c:230

but task is already holding lock:
000000000afbf30c (iowarrior_open_disc_lock){+.+.}, at:  
iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (iowarrior_open_disc_lock){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        iowarrior_open+0x8a/0x2a0 drivers/usb/misc/iowarrior.c:600
        usb_open+0x1df/0x270 drivers/usb/core/file.c:48
        chrdev_open+0x219/0x5c0 fs/char_dev.c:414
        do_dentry_open+0x494/0x1120 fs/open.c:797
        do_last fs/namei.c:3416 [inline]
        path_openat+0x1430/0x3f50 fs/namei.c:3533
        do_filp_open+0x1a1/0x280 fs/namei.c:3563
        do_sys_open+0x3c0/0x580 fs/open.c:1089
        do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (iowarrior_mutex){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        iowarrior_open+0x23/0x2a0 drivers/usb/misc/iowarrior.c:589
        usb_open+0x1df/0x270 drivers/usb/core/file.c:48
        chrdev_open+0x219/0x5c0 fs/char_dev.c:414
        do_dentry_open+0x494/0x1120 fs/open.c:797
        do_last fs/namei.c:3416 [inline]
        path_openat+0x1430/0x3f50 fs/namei.c:3533
        do_filp_open+0x1a1/0x280 fs/namei.c:3563
        do_sys_open+0x3c0/0x580 fs/open.c:1089
        do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (minor_rwsem){++++}:
        check_prev_add kernel/locking/lockdep.c:2405 [inline]
        check_prevs_add kernel/locking/lockdep.c:2507 [inline]
        validate_chain kernel/locking/lockdep.c:2897 [inline]
        __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880
        lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
        down_write+0x92/0x150 kernel/locking/rwsem.c:1500
        usb_deregister_dev drivers/usb/core/file.c:238 [inline]
        usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230
        iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873
        usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
        __device_release_driver drivers/base/dd.c:1120 [inline]
        device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
        bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
        device_del+0x420/0xb10 drivers/base/core.c:2288
        usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
        usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
        hub_port_connect drivers/usb/core/hub.c:4949 [inline]
        hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
        port_event drivers/usb/core/hub.c:5359 [inline]
        hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
        process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
        worker_thread+0x96/0xe20 kernel/workqueue.c:2415
        kthread+0x318/0x420 kernel/kthread.c:255
        ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

other info that might help us debug this:

Chain exists of:
   minor_rwsem --> iowarrior_mutex --> iowarrior_open_disc_lock

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(iowarrior_open_disc_lock);
                                lock(iowarrior_mutex);
                                lock(iowarrior_open_disc_lock);
   lock(minor_rwsem);

  *** DEADLOCK ***

6 locks held by kworker/0:2/105:
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at:  
__write_once_size include/linux/compiler.h:226 [inline]
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at:  
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set  
include/asm-generic/atomic-instrumented.h:855 [inline]
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at:  
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data  
kernel/workqueue.c:620 [inline]
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at:  
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
  #0: 00000000aba84ede ((wq_completion)usb_hub_wq){+.+.}, at:  
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
  #1: 0000000058d65fe1 ((work_completion)(&hub->events)){+.+.}, at:  
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
  #2: 000000006a2f7a8f (&dev->mutex){....}, at: device_lock  
include/linux/device.h:1220 [inline]
  #2: 000000006a2f7a8f (&dev->mutex){....}, at: hub_event+0x17c/0x3640  
drivers/usb/core/hub.c:5387
  #3: 00000000eddd5fcd (&dev->mutex){....}, at: device_lock  
include/linux/device.h:1220 [inline]
  #3: 00000000eddd5fcd (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0  
drivers/usb/core/hub.c:2190
  #4: 000000009478eeb7 (&dev->mutex){....}, at:  
device_release_driver_internal+0x23/0x4c0 drivers/base/dd.c:1148
  #5: 000000000afbf30c (iowarrior_open_disc_lock){+.+.}, at:  
iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867

stack backtrace:
CPU: 0 PID: 105 Comm: kworker/0:2 Not tainted 5.3.0-rc2+ #24
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+0xca/0x13e lib/dump_stack.c:113
  check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741
  check_prev_add kernel/locking/lockdep.c:2405 [inline]
  check_prevs_add kernel/locking/lockdep.c:2507 [inline]
  validate_chain kernel/locking/lockdep.c:2897 [inline]
  __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880
  lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
  down_write+0x92/0x150 kernel/locking/rwsem.c:1500
  usb_deregister_dev drivers/usb/core/file.c:238 [inline]
  usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230
  iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873
  usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
  __device_release_driver drivers/base/dd.c:1120 [inline]
  device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
  bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
  device_del+0x420/0xb10 drivers/base/core.c:2288
  usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
  usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
  hub_port_connect drivers/usb/core/hub.c:4949 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
  port_event drivers/usb/core/hub.c:5359 [inline]
  hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
iowarrior 4-1:0.236: I/O-Warror #0 now disconnected
usb 4-1: new high-speed USB device number 86 using dummy_hcd
usb 4-1: Using ep0 maxpacket: 8
usb 4-1: config 0 has an invalid interface number: 171 but max is 0
usb 4-1: config 0 has no interface number 0
usb 4-1: New USB device found, idVendor=14f7, idProduct=0500,  
bcdDevice=ac.d6
usb 4-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 4-1: config 0 descriptor??
technisat-usb2: could not set alternate setting to 0
technisat-usb2: firmware version: 251.126
dvb-usb: found a 'Technisat SkyStar USB HD (DVB-S/S2)' in warm state.
dvb-usb: will pass the complete MPEG2 transport stream to the software  
demuxer.
dvbdev: DVB: registering new adapter (Technisat SkyStar USB HD (DVB-S/S2))
usb 4-1: media controller created
technisat-usb2: i2c-error: out failed 53 = -22
dvb-usb: MAC address reading failed.
dvbdev: dvb_create_media_entity: media entity 'dvb-demux' registered.
technisat-usb2: i2c-error: out failed 68 = -22
dvb-usb: no frontend was attached by 'Technisat SkyStar USB HD (DVB-S/S2)'
Registered IR keymap rc-technisat-usb2
rc_core: Loaded IR protocol module ir-rc5-decoder, but protocol rc-5 still  
not available
rc rc0: Technisat SkyStar USB HD (DVB-S/S2) as  
/devices/platform/dummy_hcd.3/usb4/4-1/rc/rc0
input: Technisat SkyStar USB HD (DVB-S/S2) as  
/devices/platform/dummy_hcd.3/usb4/4-1/rc/rc0/input262
dvb-usb: schedule remote query interval to 100 msecs.
dvb-usb: Technisat SkyStar USB HD (DVB-S/S2) successfully initialized and  
connected.
usb 4-1: USB disconnect, device number 86
dvb-usb: Technisat SkyStar USB HD (DVB-S/S2) successfully deinitialized and  
disconnected.
usb 5-1: USB disconnect, device number 48
usb 2-1: USB disconnect, device number 98
metro-usb ttyUSB0: Metrologic USB to Serial converter now disconnected from  
ttyUSB0
metro_usb 2-1:0.123: device disconnected
usb 2-1: new low-speed USB device number 99 using dummy_hcd
usb 2-1: config index 0 descriptor too short (expected 63259, got 46)
usb 2-1: config 0 has an invalid interface number: 123 but max is 0
usb 2-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 2-1: config 0 has no interface number 0
usb 2-1: config 0 interface 123 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 2-1: New USB device found, idVendor=0c2e, idProduct=0720,  
bcdDevice=43.fe
usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 2-1: config 0 descriptor??
metro_usb 2-1:0.123: Metrologic USB to Serial converter detected
usb 2-1: Metrologic USB to Serial converter now attached to ttyUSB0
usb 4-1: new high-speed USB device number 89 using dummy_hcd
usb 4-1: Using ep0 maxpacket: 8
usb 4-1: config 0 has an invalid interface number: 171 but max is 0
usb 4-1: config 0 has no interface number 0
usb 4-1: New USB device found, idVendor=14f7, idProduct=0500,  
bcdDevice=ac.d6
usb 4-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 4-1: config 0 descriptor??
technisat-usb2: could not set alternate setting to 0
technisat-usb2: firmware version: 25.147
dvb-usb: found a 'Technisat SkyStar USB HD (DVB-S/S2)' in warm state.
dvb-usb: will pass the complete MPEG2 transport stream to the software  
demuxer.
dvbdev: DVB: registering new adapter (Technisat SkyStar USB HD (DVB-S/S2))
usb 4-1: media controller created
technisat-usb2: i2c-error: out failed 53 = -22
dvb-usb: MAC address reading failed.
dvbdev: dvb_create_media_entity: media entity 'dvb-demux' registered.
technisat-usb2: i2c-error: out failed 68 = -22
dvb-usb: no frontend was attached by 'Technisat SkyStar USB HD (DVB-S/S2)'
Registered IR keymap rc-technisat-usb2
rc_core: Loaded IR protocol module ir-rc5-decoder, but protocol rc-5 still  
not available
rc rc0: Technisat SkyStar USB HD (DVB-S/S2) as  
/devices/platform/dummy_hcd.3/usb4/4-1/rc/rc0
input: Technisat SkyStar USB HD (DVB-S/S2) as  
/devices/platform/dummy_hcd.3/usb4/4-1/rc/rc0/input265
dvb-usb: schedule remote query interval to 100 msecs.
dvb-usb: Technisat SkyStar USB HD (DVB-S/S2) successfully initialized and  
connected.
usb 4-1: USB disconnect, device number 89
dvb-usb: Technisat SkyStar USB HD (DVB-S/S2) successfully deinitialized and  
disconnected.
usb 4-1: new high-speed USB device number 90 using dummy_hcd
usb 4-1: Using ep0 maxpacket: 8
usb 4-1: config 0 has an invalid interface number: 171 but max is 0
usb 4-1: config 0 has no interface number 0
usb 4-1: New USB device found, idVendor=14f7, idProduct=0500,  
bcdDevice=ac.d6
usb 4-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 4-1: config 0 descriptor??
technisat-usb2: could not set alternate setting to 0
technisat-usb2: firmware version: 39.225
dvb-usb: found a 'Technisat SkyStar USB HD (DVB-S/S2)' in warm state.
dvb-usb: will pass the complete MPEG2 transport stream to the software  
demuxer.
dvbdev: DVB: registering new adapter (Technisat SkyStar USB HD (DVB-S/S2))
usb 4-1: media controller created
technisat-usb2: i2c-error: out failed 53 = -22
dvb-usb: MAC address reading failed.
dvbdev: dvb_create_media_entity: media entity 'dvb-demux' registered.
technisat-usb2: i2c-error: out failed 68 = -22
dvb-usb: no frontend was attached by 'Technisat SkyStar USB HD (DVB-S/S2)'
Registered IR keymap rc-technisat-usb2
rc_core: Loaded IR protocol module ir-rc5-decoder, but protocol rc-5 still  
not available
rc rc0: Technisat SkyStar USB HD (DVB-S/S2) as  
/devices/platform/dummy_hcd.3/usb4/4-1/rc/rc0
input: Technisat SkyStar USB HD (DVB-S/S2) as  
/devices/platform/dummy_hcd.3/usb4/4-1/rc/rc0/input266
dvb-usb: schedule remote query interval to 100 msecs.
dvb-usb: Technisat SkyStar USB HD (DVB-S/S2) successfully initialized and  
connected.
usb 4-1: USB disconnect, device number 90
dvb-usb: Technisat SkyStar USB HD (DVB-S/S2) successfully deinitialized and  
disconnected.


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: Re: possible deadlock in usb_deregister_dev
  2019-08-06 14:22 ` Oliver Neukum
@ 2019-08-06 14:22   ` syzbot
  0 siblings, 0 replies; 7+ messages in thread
From: syzbot @ 2019-08-06 14:22 UTC (permalink / raw)
  To: Oliver Neukum
  Cc: andreyknvl, gregkh, linux-kernel, linux-usb, oneukum, syzkaller-bugs

> Am Montag, den 05.08.2019, 04:58 -0700 schrieb syzbot:
>> Hello,

>> syzbot found the following crash on:

>> HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
>> git tree:       https://github.com/google/kasan.git usb-fuzzer
>> console output: https://syzkaller.appspot.com/x/log.txt?x=13b5bc8a600000
>> kernel config:   
>> https://syzkaller.appspot.com/x/.config?x=792eb47789f57810
>> dashboard link:  
>> https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
>> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

>> Unfortunately, I don't have any reproducer for this crash yet.

>> IMPORTANT: if you fix the bug, please add the following tag to the  
>> commit:
>> Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com

> #syz test: https://github.com/google/kasan.git e96407b4

This crash does not have a reproducer. I cannot test it.


>  From 973e82b3f583113e4d7fe5cd2f918a16022c4e38 Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <oneukum@suse.com>
> Date: Tue, 6 Aug 2019 16:17:54 +0200
> Subject: [PATCH] usb: iowarrior: fix deadlock on disconnect

> We have to drop the mutex before we close() upon disconnect()
> as close() needs the lock. This is safe to do by dropping the
> mutex as intfdata is already set to NULL, so open() will fail.

> Fixes: 03f36e885fc26 ("USB: open disconnect race in iowarrior")
> Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
> Signed-off-by: Oliver Neukum <oneukum@suse.com>
> ---
>   drivers/usb/misc/iowarrior.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)

> diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
> index ba05dd80a020..f5bed9f29e56 100644
> --- a/drivers/usb/misc/iowarrior.c
> +++ b/drivers/usb/misc/iowarrior.c
> @@ -866,19 +866,20 @@ static void iowarrior_disconnect(struct  
> usb_interface *interface)
>   	dev = usb_get_intfdata(interface);
>   	mutex_lock(&iowarrior_open_disc_lock);
>   	usb_set_intfdata(interface, NULL);
> +	/* prevent device read, write and ioctl */
> +	dev->present = 0;

>   	minor = dev->minor;
> +	mutex_unlock(&iowarrior_open_disc_lock);
> +	/* give back our minor - this will call close() locks need to be  
> dropped at this point*/

> -	/* give back our minor */
>   	usb_deregister_dev(interface, &iowarrior_class);

>   	mutex_lock(&dev->mutex);

>   	/* prevent device read, write and ioctl */
> -	dev->present = 0;

>   	mutex_unlock(&dev->mutex);
> -	mutex_unlock(&iowarrior_open_disc_lock);

>   	if (dev->opened) {
>   		/* There is a process that holds a filedescriptor to the device ,
> --
> 2.16.4


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: possible deadlock in usb_deregister_dev
  2019-08-05 11:58 possible deadlock in usb_deregister_dev syzbot
  2019-08-06 14:22 ` Oliver Neukum
@ 2019-08-09 18:18 ` syzbot
  2019-08-09 19:32   ` Alan Stern
  1 sibling, 1 reply; 7+ messages in thread
From: syzbot @ 2019-08-09 18:18 UTC (permalink / raw)
  To: andreyknvl, gregkh, linux-kernel, linux-usb, oneukum, syzkaller-bugs

syzbot has found a reproducer for the following crash on:

HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=15bf780e600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
dashboard link: https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16787574600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=136cc4d2600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com

usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 2
======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc2+ #25 Not tainted
------------------------------------------------------
kworker/0:1/12 is trying to acquire lock:
00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev  
drivers/usb/core/file.c:238 [inline]
00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev+0x61/0x270  
drivers/usb/core/file.c:230

but task is already holding lock:
000000001d1989ef (iowarrior_open_disc_lock){+.+.}, at:  
iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (iowarrior_open_disc_lock){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        iowarrior_open+0x8a/0x2a0 drivers/usb/misc/iowarrior.c:600
        usb_open+0x1df/0x270 drivers/usb/core/file.c:48
        chrdev_open+0x219/0x5c0 fs/char_dev.c:414
        do_dentry_open+0x494/0x1120 fs/open.c:797
        do_last fs/namei.c:3416 [inline]
        path_openat+0x1430/0x3f50 fs/namei.c:3533
        do_filp_open+0x1a1/0x280 fs/namei.c:3563
        do_sys_open+0x3c0/0x580 fs/open.c:1089
        do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (iowarrior_mutex){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        iowarrior_open+0x23/0x2a0 drivers/usb/misc/iowarrior.c:589
        usb_open+0x1df/0x270 drivers/usb/core/file.c:48
        chrdev_open+0x219/0x5c0 fs/char_dev.c:414
        do_dentry_open+0x494/0x1120 fs/open.c:797
        do_last fs/namei.c:3416 [inline]
        path_openat+0x1430/0x3f50 fs/namei.c:3533
        do_filp_open+0x1a1/0x280 fs/namei.c:3563
        do_sys_open+0x3c0/0x580 fs/open.c:1089
        do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (minor_rwsem){++++}:
        check_prev_add kernel/locking/lockdep.c:2405 [inline]
        check_prevs_add kernel/locking/lockdep.c:2507 [inline]
        validate_chain kernel/locking/lockdep.c:2897 [inline]
        __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880
        lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
        down_write+0x92/0x150 kernel/locking/rwsem.c:1500
        usb_deregister_dev drivers/usb/core/file.c:238 [inline]
        usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230
        iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873
        usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
        __device_release_driver drivers/base/dd.c:1120 [inline]
        device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
        bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
        device_del+0x420/0xb10 drivers/base/core.c:2288
        usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
        usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
        hub_port_connect drivers/usb/core/hub.c:4949 [inline]
        hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
        port_event drivers/usb/core/hub.c:5359 [inline]
        hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
        process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
        worker_thread+0x96/0xe20 kernel/workqueue.c:2415
        kthread+0x318/0x420 kernel/kthread.c:255
        ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

other info that might help us debug this:

Chain exists of:
   minor_rwsem --> iowarrior_mutex --> iowarrior_open_disc_lock

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(iowarrior_open_disc_lock);
                                lock(iowarrior_mutex);
                                lock(iowarrior_open_disc_lock);
   lock(minor_rwsem);

  *** DEADLOCK ***

6 locks held by kworker/0:1/12:
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
__write_once_size include/linux/compiler.h:226 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set  
include/asm-generic/atomic-instrumented.h:855 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data  
kernel/workqueue.c:620 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
  #1: 0000000001908f5f ((work_completion)(&hub->events)){+.+.}, at:  
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
  #2: 00000000894e02c9 (&dev->mutex){....}, at: device_lock  
include/linux/device.h:1220 [inline]
  #2: 00000000894e02c9 (&dev->mutex){....}, at: hub_event+0x17c/0x3640  
drivers/usb/core/hub.c:5387
  #3: 00000000e2dd0256 (&dev->mutex){....}, at: device_lock  
include/linux/device.h:1220 [inline]
  #3: 00000000e2dd0256 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0  
drivers/usb/core/hub.c:2190
  #4: 0000000021bbb80a (&dev->mutex){....}, at:  
device_release_driver_internal+0x23/0x4c0 drivers/base/dd.c:1148
  #5: 000000001d1989ef (iowarrior_open_disc_lock){+.+.}, at:  
iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867

stack backtrace:
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc2+ #25
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+0xca/0x13e lib/dump_stack.c:113
  check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741
  check_prev_add kernel/locking/lockdep.c:2405 [inline]
  check_prevs_add kernel/locking/lockdep.c:2507 [inline]
  validate_chain kernel/locking/lockdep.c:2897 [inline]
  __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880
  lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
  down_write+0x92/0x150 kernel/locking/rwsem.c:1500
  usb_deregister_dev drivers/usb/core/file.c:238 [inline]
  usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230
  iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873
  usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
  __device_release_driver drivers/base/dd.c:1120 [inline]
  device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
  bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
  device_del+0x420/0xb10 drivers/base/core.c:2288
  usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
  usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
  hub_port_connect drivers/usb/core/hub.c:4949 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
  port_event drivers/usb/core/hub.c:5359 [inline]
  hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 3 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 5
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 6 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 7
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 8 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 8
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 9 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 9
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 10 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 11
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: possible deadlock in usb_deregister_dev
  2019-08-09 18:18 ` syzbot
@ 2019-08-09 19:32   ` Alan Stern
  2019-08-12 12:11     ` Andrey Konovalov
  0 siblings, 1 reply; 7+ messages in thread
From: Alan Stern @ 2019-08-09 19:32 UTC (permalink / raw)
  To: syzbot
  Cc: andreyknvl, gregkh, linux-kernel, linux-usb, oneukum, syzkaller-bugs

On Fri, 9 Aug 2019, syzbot wrote:

> syzbot has found a reproducer for the following crash on:
> 
> HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=15bf780e600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
> dashboard link: https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16787574600000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=136cc4d2600000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
> 
> usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> usb 1-1: config 0 descriptor??
> iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
> attached to iowarrior0
> usb 1-1: USB disconnect, device number 2
> ======================================================
> WARNING: possible circular locking dependency detected
> 5.3.0-rc2+ #25 Not tainted
> ------------------------------------------------------
> kworker/0:1/12 is trying to acquire lock:
> 00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev  
> drivers/usb/core/file.c:238 [inline]
> 00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev+0x61/0x270  
> drivers/usb/core/file.c:230
> 
> but task is already holding lock:
> 000000001d1989ef (iowarrior_open_disc_lock){+.+.}, at:  
> iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867
> 
> which lock already depends on the new lock.

https://syzkaller.appspot.com/bug?extid=ca52394faa436d8131df is 
undoubtedly a duplicate of this.

Alan Stern


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: possible deadlock in usb_deregister_dev
  2019-08-09 19:32   ` Alan Stern
@ 2019-08-12 12:11     ` Andrey Konovalov
  2019-08-12 12:31       ` syzbot
  0 siblings, 1 reply; 7+ messages in thread
From: Andrey Konovalov @ 2019-08-12 12:11 UTC (permalink / raw)
  To: Alan Stern
  Cc: syzbot, Greg Kroah-Hartman, LKML, USB list, oneukum, syzkaller-bugs

[-- Attachment #1: Type: text/plain, Size: 2126 bytes --]

On Fri, Aug 9, 2019 at 9:32 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Fri, 9 Aug 2019, syzbot wrote:
>
> > syzbot has found a reproducer for the following crash on:
> >
> > HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15bf780e600000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16787574600000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=136cc4d2600000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
> >
> > usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> > usb 1-1: config 0 descriptor??
> > iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now
> > attached to iowarrior0
> > usb 1-1: USB disconnect, device number 2
> > ======================================================
> > WARNING: possible circular locking dependency detected
> > 5.3.0-rc2+ #25 Not tainted
> > ------------------------------------------------------
> > kworker/0:1/12 is trying to acquire lock:
> > 00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev
> > drivers/usb/core/file.c:238 [inline]
> > 00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev+0x61/0x270
> > drivers/usb/core/file.c:230
> >
> > but task is already holding lock:
> > 000000001d1989ef (iowarrior_open_disc_lock){+.+.}, at:
> > iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867
> >
> > which lock already depends on the new lock.
>
> https://syzkaller.appspot.com/bug?extid=ca52394faa436d8131df is
> undoubtedly a duplicate of this.

I've marked it as one, thanks!

Now that we have a reproducer, let's retry Oliver's fix:

#syz test: https://github.com/google/kasan.git e96407b4

[-- Attachment #2: iowarrior.patch --]
[-- Type: text/x-patch, Size: 952 bytes --]

diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
index ba05dd80a020..f5bed9f29e56 100644
--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -866,19 +866,20 @@ static void iowarrior_disconnect(struct usb_interface *interface)
 	dev = usb_get_intfdata(interface);
 	mutex_lock(&iowarrior_open_disc_lock);
 	usb_set_intfdata(interface, NULL);
+	/* prevent device read, write and ioctl */
+	dev->present = 0;
 
 	minor = dev->minor;
+	mutex_unlock(&iowarrior_open_disc_lock);
+	/* give back our minor - this will call close() locks need to be dropped at this point*/
 
-	/* give back our minor */
 	usb_deregister_dev(interface, &iowarrior_class);
 
 	mutex_lock(&dev->mutex);
 
 	/* prevent device read, write and ioctl */
-	dev->present = 0;
 
 	mutex_unlock(&dev->mutex);
-	mutex_unlock(&iowarrior_open_disc_lock);
 
 	if (dev->opened) {
 		/* There is a process that holds a filedescriptor to the device ,

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: possible deadlock in usb_deregister_dev
  2019-08-12 12:11     ` Andrey Konovalov
@ 2019-08-12 12:31       ` syzbot
  0 siblings, 0 replies; 7+ messages in thread
From: syzbot @ 2019-08-12 12:31 UTC (permalink / raw)
  To: andreyknvl, gregkh, linux-kernel, linux-usb, oneukum, stern,
	syzkaller-bugs

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger  
crash:

Reported-and-tested-by:  
syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com

Tested on:

commit:         e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16a8a38c600000

Note: testing is done by a robot and is best-effort only.

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: possible deadlock in usb_deregister_dev
  2019-08-05 11:58 possible deadlock in usb_deregister_dev syzbot
@ 2019-08-06 14:22 ` Oliver Neukum
  2019-08-06 14:22   ` syzbot
  2019-08-09 18:18 ` syzbot
  1 sibling, 1 reply; 7+ messages in thread
From: Oliver Neukum @ 2019-08-06 14:22 UTC (permalink / raw)
  To: syzbot, andreyknvl, syzkaller-bugs, gregkh, linux-kernel, linux-usb

Am Montag, den 05.08.2019, 04:58 -0700 schrieb syzbot:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=13b5bc8a600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=792eb47789f57810
> dashboard link: https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com

#syz test: https://github.com/google/kasan.git e96407b4

From 973e82b3f583113e4d7fe5cd2f918a16022c4e38 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Tue, 6 Aug 2019 16:17:54 +0200
Subject: [PATCH] usb: iowarrior: fix deadlock on disconnect

We have to drop the mutex before we close() upon disconnect()
as close() needs the lock. This is safe to do by dropping the
mutex as intfdata is already set to NULL, so open() will fail.

Fixes: 03f36e885fc26 ("USB: open disconnect race in iowarrior")
Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/misc/iowarrior.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
index ba05dd80a020..f5bed9f29e56 100644
--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -866,19 +866,20 @@ static void iowarrior_disconnect(struct usb_interface *interface)
 	dev = usb_get_intfdata(interface);
 	mutex_lock(&iowarrior_open_disc_lock);
 	usb_set_intfdata(interface, NULL);
+	/* prevent device read, write and ioctl */
+	dev->present = 0;
 
 	minor = dev->minor;
+	mutex_unlock(&iowarrior_open_disc_lock);
+	/* give back our minor - this will call close() locks need to be dropped at this point*/
 
-	/* give back our minor */
 	usb_deregister_dev(interface, &iowarrior_class);
 
 	mutex_lock(&dev->mutex);
 
 	/* prevent device read, write and ioctl */
-	dev->present = 0;
 
 	mutex_unlock(&dev->mutex);
-	mutex_unlock(&iowarrior_open_disc_lock);
 
 	if (dev->opened) {
 		/* There is a process that holds a filedescriptor to the device ,
-- 
2.16.4


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, back to index

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-05 11:58 possible deadlock in usb_deregister_dev syzbot
2019-08-06 14:22 ` Oliver Neukum
2019-08-06 14:22   ` syzbot
2019-08-09 18:18 ` syzbot
2019-08-09 19:32   ` Alan Stern
2019-08-12 12:11     ` Andrey Konovalov
2019-08-12 12:31       ` syzbot

Linux-USB Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-usb/0 linux-usb/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-usb linux-usb/ https://lore.kernel.org/linux-usb \
		linux-usb@vger.kernel.org linux-usb@archiver.kernel.org
	public-inbox-index linux-usb

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-usb


AGPL code for this site: git clone https://public-inbox.org/ public-inbox