Date:	Thu, 23 Jul 2015 15:31:46 +0200
From:	Andrey Konovalov <andreyknvl@...gle.com>
To:	Pali Rohár <pali.rohar@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Mathias Gottschlag <mgottschlag@...il.com>,
	Shailendra Verma <shailendra.capricorn@...il.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"Luis R. Rodriguez" <mcgrof@...e.com>,
	Thomas Hellstrom <thellstrom@...are.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>, ktsan@...glegroups.com
Subject: Re: Potential data race in psmouse_interrupt

Hi Pali,

There are a few reports in psmouse-base.c/alps.c code as well.
Here is a couple of them that are printed one right after another.
The second one tells about a race on ps2dev->cmdcnt.

==================================================================
ThreadSanitizer: data-race in ps2_handle_ack

Write of size 8 by thread T6 (K6):
 [<ffffffff819c0b83>] ps2_handle_ack+0xf3/0x180 drivers/input/serio/libps2.c:322
 [<ffffffff819d55d7>] psmouse_interrupt+0x207/0x690
drivers/input/mouse/psmouse-base.c:317
 [<ffffffff819bcf46>] serio_interrupt+0x66/0xb0 drivers/input/serio/serio.c:1008
 [<ffffffff819be820>] i8042_interrupt+0x240/0x4d0
drivers/input/serio/i8042.c:541
 [<ffffffff810f03b2>] handle_irq_event_percpu+0x62/0x2a0 kernel/irq/handle.c:143
 [<ffffffff810f0692>] handle_irq_event+0xa2/0xf0 kernel/irq/handle.c:192
 [<ffffffff810f5414>] handle_edge_irq+0x104/0x380 kernel/irq/chip.c:608
 [<     inlined    >] handle_irq+0xf6/0x220 generic_handle_irq_desc
include/linux/irqdesc.h:146
 [<ffffffff81009f86>] handle_irq+0xf6/0x220 arch/x86/kernel/irq_64.c:81
 [<ffffffff810093ce>] do_IRQ+0x5e/0x110 arch/x86/kernel/irq.c:223
 [<ffffffff81e728ab>] ret_from_intr+0x0/0x1f arch/x86/entry/entry_64.S:601
 [<     inlined    >] irq_exit+0x98/0xa0 invoke_softirq kernel/softirq.c:350
 [<ffffffff8108edd8>] irq_exit+0x98/0xa0 kernel/softirq.c:391
 [<     inlined    >] smp_apic_timer_interrupt+0x63/0x80 exiting_irq
./arch/x86/include/asm/apic.h:655
 [<ffffffff8105c503>] smp_apic_timer_interrupt+0x63/0x80
arch/x86/kernel/apic/apic.c:915
 [<ffffffff81e72b9b>] apic_timer_interrupt+0x6b/0x70
arch/x86/entry/entry_64.S:782
 [<ffffffff81086fe3>] _do_fork+0x133/0x500 kernel/fork.c:1719
 [<ffffffff810873ec>] kernel_thread+0x3c/0x60 kernel/fork.c:1772
 [<ffffffff810a71dc>] __call_usermodehelper+0x5c/0x90 kernel/kmod.c:317
 [<ffffffff810adcf9>] process_one_work+0x2a9/0x6d0 kernel/workqueue.c:2036
 [<ffffffff810aeddf>] worker_thread+0xbf/0x710 kernel/workqueue.c:2170
 [<ffffffff810b700c>] kthread+0x15c/0x180 kernel/kthread.c:207
 [<ffffffff81e7215f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526
DBG: cpu = ffff88053fd9fe68
DBG: cpu id = 3

Previous read of size 8 by thread T397 (K394):
 [<ffffffff819c0cf2>] ps2_sendbyte+0xe2/0x210 drivers/input/serio/libps2.c:45
 [<ffffffff819c1109>] __ps2_command+0x159/0x660 drivers/input/serio/libps2.c:214
 [<ffffffff819c1645>] ps2_command+0x35/0x60 drivers/input/serio/libps2.c:260
 [<ffffffff819dd412>] alps_rpt_cmd+0x42/0xe0
drivers/input/mouse/alps.c:1665 (discriminator 1)
 [<ffffffff819e12b6>] alps_identify+0x36/0xc80 drivers/input/mouse/alps.c:2690
 [<ffffffff819e3498>] alps_detect+0x28/0x150 drivers/input/mouse/alps.c:2960
 [<     inlined    >] psmouse_extensions+0x25e/0x4e0 psmouse_do_detect
drivers/input/mouse/psmouse-base.c:752
 [<ffffffff819d60fe>] psmouse_extensions+0x25e/0x4e0
drivers/input/mouse/psmouse-base.c:870
 [<ffffffff819d662d>] psmouse_switch_protocol+0x2ad/0x330
drivers/input/mouse/psmouse-base.c:1467
 [<ffffffff819d7656>] psmouse_connect+0x2e6/0x450
drivers/input/mouse/psmouse-base.c:1554 (discriminator 4)
 [<     inlined    >] serio_driver_probe+0x57/0x80
serio_connect_driver drivers/input/serio/serio.c:65
 [<ffffffff819bd1a7>] serio_driver_probe+0x57/0x80
drivers/input/serio/serio.c:796
 [<     inlined    >] driver_probe_device+0x1da/0x460 really_probe
drivers/base/dd.c:308
 [<ffffffff81813d4a>] driver_probe_device+0x1da/0x460 drivers/base/dd.c:414
 [<ffffffff81814094>] __driver_attach+0xc4/0xd0 drivers/base/dd.c:612
 [<ffffffff81810b63>] bus_for_each_dev+0x93/0xe0 drivers/base/bus.c:314
 [<ffffffff81813583>] driver_attach+0x33/0x50 drivers/base/dd.c:631
 [<     inlined    >] serio_handle_event+0x2d3/0x3b0
serio_attach_driver drivers/input/serio/serio.c:826
 [<ffffffff819bdb13>] serio_handle_event+0x2d3/0x3b0
drivers/input/serio/serio.c:245
 [<ffffffff810adcf9>] process_one_work+0x2a9/0x6d0 kernel/workqueue.c:2036
 [<ffffffff810aeddf>] worker_thread+0xbf/0x710 kernel/workqueue.c:2170
 [<ffffffff810b700c>] kthread+0x15c/0x180 kernel/kthread.c:207
 [<ffffffff81e7215f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526
DBG: cpu = 0

DBG: addr: ffff88019a923a58
DBG: first offset: 0, second offset: 0
DBG: T6 clock: {T6: 2264295, T397: 174118}
DBG: T397 clock: {T397: 174122}
==================================================================
==================================================================
ThreadSanitizer: data-race in __ps2_command

Read of size 1 by thread T397 (K394):
 [<ffffffff819c1220>] __ps2_command+0x270/0x660
drivers/input/serio/libps2.c:230 (discriminator 21)
 [<ffffffff819c1645>] ps2_command+0x35/0x60 drivers/input/serio/libps2.c:260
 [<ffffffff819dd47e>] alps_rpt_cmd+0xae/0xe0 drivers/input/mouse/alps.c:1674
 [<ffffffff819e12b6>] alps_identify+0x36/0xc80 drivers/input/mouse/alps.c:2690
 [<ffffffff819e3498>] alps_detect+0x28/0x150 drivers/input/mouse/alps.c:2960
 [<     inlined    >] psmouse_extensions+0x25e/0x4e0 psmouse_do_detect
drivers/input/mouse/psmouse-base.c:752
 [<ffffffff819d60fe>] psmouse_extensions+0x25e/0x4e0
drivers/input/mouse/psmouse-base.c:870
 [<ffffffff819d662d>] psmouse_switch_protocol+0x2ad/0x330
drivers/input/mouse/psmouse-base.c:1467
 [<ffffffff819d7656>] psmouse_connect+0x2e6/0x450
drivers/input/mouse/psmouse-base.c:1554 (discriminator 4)
 [<     inlined    >] serio_driver_probe+0x57/0x80
serio_connect_driver drivers/input/serio/serio.c:65
 [<ffffffff819bd1a7>] serio_driver_probe+0x57/0x80
drivers/input/serio/serio.c:796
 [<     inlined    >] driver_probe_device+0x1da/0x460 really_probe
drivers/base/dd.c:308
 [<ffffffff81813d4a>] driver_probe_device+0x1da/0x460 drivers/base/dd.c:414
 [<ffffffff81814094>] __driver_attach+0xc4/0xd0 drivers/base/dd.c:612
 [<ffffffff81810b63>] bus_for_each_dev+0x93/0xe0 drivers/base/bus.c:314
 [<ffffffff81813583>] driver_attach+0x33/0x50 drivers/base/dd.c:631
 [<     inlined    >] serio_handle_event+0x2d3/0x3b0
serio_attach_driver drivers/input/serio/serio.c:826
 [<ffffffff819bdb13>] serio_handle_event+0x2d3/0x3b0
drivers/input/serio/serio.c:245
 [<ffffffff810adcf9>] process_one_work+0x2a9/0x6d0 kernel/workqueue.c:2036
 [<ffffffff810aeddf>] worker_thread+0xbf/0x710 kernel/workqueue.c:2170
 [<ffffffff810b700c>] kthread+0x15c/0x180 kernel/kthread.c:207
 [<ffffffff81e7215f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526
DBG: cpu = ffff88053fc9fe68
DBG: cpu id = 1

Previous write of size 1 by thread T6 (K6):
 [<ffffffff819c09a6>] ps2_handle_response+0x46/0x130
drivers/input/serio/libps2.c:346
 [<ffffffff819d58a4>] psmouse_interrupt+0x4d4/0x690
drivers/input/mouse/psmouse-base.c:321
 [<ffffffff819bcf46>] serio_interrupt+0x66/0xb0 drivers/input/serio/serio.c:1008
 [<ffffffff819be820>] i8042_interrupt+0x240/0x4d0
drivers/input/serio/i8042.c:541
 [<ffffffff810f03b2>] handle_irq_event_percpu+0x62/0x2a0 kernel/irq/handle.c:143
 [<ffffffff810f0692>] handle_irq_event+0xa2/0xf0 kernel/irq/handle.c:192
 [<ffffffff810f5414>] handle_edge_irq+0x104/0x380 kernel/irq/chip.c:608
 [<     inlined    >] handle_irq+0xf6/0x220 generic_handle_irq_desc
include/linux/irqdesc.h:146
 [<ffffffff81009f86>] handle_irq+0xf6/0x220 arch/x86/kernel/irq_64.c:81
 [<ffffffff810093ce>] do_IRQ+0x5e/0x110 arch/x86/kernel/irq.c:223
 [<ffffffff81e728ab>] ret_from_intr+0x0/0x1f arch/x86/entry/entry_64.S:601
 [<ffffffff81e72b9b>] apic_timer_interrupt+0x6b/0x70
arch/x86/entry/entry_64.S:782
 [<     inlined    >] kvm_clock_get_cycles+0x3e/0x50 kvm_clock_read
arch/x86/kernel/kvmclock.c:85
 [<ffffffff8106e74e>] kvm_clock_get_cycles+0x3e/0x50
arch/x86/kernel/kvmclock.c:92
 [<     inlined    >] ktime_get_with_offset+0x99/0x180
timekeeping_get_delta kernel/time/timekeeping.c:210
 [<     inlined    >] ktime_get_with_offset+0x99/0x180
timekeeping_get_ns kernel/time/timekeeping.c:306
 [<ffffffff81114da9>] ktime_get_with_offset+0x99/0x180
kernel/time/timekeeping.c:720
 [<     inlined    >] copy_process.part.44+0x773/0x2c40
ktime_get_boottime include/linux/timekeeping.h:183
 [<     inlined    >] copy_process.part.44+0x773/0x2c40
ktime_get_boot_ns include/linux/timekeeping.h:214
 [<ffffffff810848b3>] copy_process.part.44+0x773/0x2c40 kernel/fork.c:1363
 [<     inlined    >] _do_fork+0x103/0x500 copy_process kernel/fork.c:1261
 [<ffffffff81086fb3>] _do_fork+0x103/0x500 kernel/fork.c:1709
 [<ffffffff810873ec>] kernel_thread+0x3c/0x60 kernel/fork.c:1772
 [<ffffffff810a71dc>] __call_usermodehelper+0x5c/0x90 kernel/kmod.c:317
 [<ffffffff810adcf9>] process_one_work+0x2a9/0x6d0 kernel/workqueue.c:2036
 [<ffffffff810aeddf>] worker_thread+0xbf/0x710 kernel/workqueue.c:2170
 [<ffffffff810b700c>] kthread+0x15c/0x180 kernel/kthread.c:207
 [<ffffffff81e7215f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526
DBG: cpu = 0

DBG: addr: ffff88019a923a68
DBG: first offset: 0, second offset: 0
DBG: T397 clock: {T397: 175738, T6: 2266233}
DBG: T6 clock: {T6: 2266336}
==================================================================

On Thu, Jul 23, 2015 at 3:08 PM, Pali Rohár <pali.rohar@...il.com> wrote:
> On Wednesday 22 July 2015 15:14:42 Andrey Konovalov wrote:
>> Hi!
>>
>> We are working on a dynamic data race detector for Linux kernel called
>> KernelThreadSanitizer (ktsan) (https://github.com/google/ktsan/wiki).
>>
>> Here is a report we got while running ktsan (upstream revision
>> 21bdb584af8cca7c6df3c44cba268be050a234eb).
>>
>> ==================================================================
>> ThreadSanitizer: data-race in psmouse_interrupt
>>
>> Write of size 1 by thread T1 (K1):
>>  [<ffffffff819d5272>] psmouse_interrupt+0xd2/0x690
>> drivers/input/mouse/psmouse-base.c:337
>>  [<ffffffff819bcd16>] serio_interrupt+0x66/0xb0 drivers/input/serio/serio.c:1008
>>  [<ffffffff819be5f0>] i8042_interrupt+0x240/0x4d0
>> drivers/input/serio/i8042.c:541
>>  [<ffffffff810f03b2>] handle_irq_event_percpu+0x62/0x2a0 kernel/irq/handle.c:143
>>  [<ffffffff810f0692>] handle_irq_event+0xa2/0xf0 kernel/irq/handle.c:192
>>  [<ffffffff810f5414>] handle_edge_irq+0x104/0x380 kernel/irq/chip.c:608
>>  [<     inlined    >] handle_irq+0xf6/0x220 generic_handle_irq_desc
>> include/linux/irqdesc.h:146
>>  [<ffffffff81009f86>] handle_irq+0xf6/0x220 arch/x86/kernel/irq_64.c:81
>>  [<ffffffff810093ce>] do_IRQ+0x5e/0x110 arch/x86/kernel/irq.c:223
>>  [<ffffffff81e726ab>] ret_from_intr+0x0/0x1f arch/x86/entry/entry_64.S:601
>>  [<     inlined    >] irq_exit+0x98/0xa0 invoke_softirq kernel/softirq.c:350
>>  [<ffffffff8108edd8>] irq_exit+0x98/0xa0 kernel/softirq.c:391
>>  [<     inlined    >] smp_apic_timer_interrupt+0x63/0x80 exiting_irq
>> ./arch/x86/include/asm/apic.h:655
>>  [<ffffffff8105c503>] smp_apic_timer_interrupt+0x63/0x80
>> arch/x86/kernel/apic/apic.c:915
>>  [<ffffffff81e7299b>] apic_timer_interrupt+0x6b/0x70
>> arch/x86/entry/entry_64.S:782
>>  [<ffffffff8153223d>] kvasprintf+0x5d/0x90 lib/kasprintf.c:24
>>  [<ffffffff815322be>] kasprintf+0x4e/0x70 lib/kasprintf.c:40
>>  [<     inlined    >] module_add_driver+0x8f/0x180 make_driver_name
>> drivers/base/module.c:18
>>  [<ffffffff8183059f>] module_add_driver+0x8f/0x180 drivers/base/module.c:63
>>  [<ffffffff81812c94>] bus_add_driver+0x204/0x340 drivers/base/bus.c:713
>>  [<ffffffff81814e2b>] driver_register+0xdb/0x190 drivers/base/driver.c:168
>>  [<ffffffff81a5ed16>] __hid_register_driver+0xb6/0x100
>> drivers/hid/hid-core.c:2677
>>  [<ffffffff825ab67d>] apple_driver_init+0x24/0x31 drivers/hid/hid-apple.c:574
>>  [<ffffffff81000339>] do_one_initcall+0xb9/0x220 init/main.c:798
>>  [<     inlined    >] kernel_init_freeable+0x2ca/0x397
>> do_initcall_level init/main.c:863
>>  [<     inlined    >] kernel_init_freeable+0x2ca/0x397 do_initcalls
>> init/main.c:871
>>  [<     inlined    >] kernel_init_freeable+0x2ca/0x397 do_basic_setup
>> init/main.c:890
>>  [<ffffffff8253d919>] kernel_init_freeable+0x2ca/0x397 init/main.c:1013
>>  [<ffffffff81e5ad66>] kernel_init+0x16/0x140 init/main.c:941
>>  [<ffffffff81e71f5f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526
>> DBG: cpu = ffff88053fd9fe68
>> DBG: cpu id = 3
>>
>> Previous read of size 1 by thread T509 (K506):
>>  [<     inlined    >] cypress_send_ext_cmd+0x193/0x500
>> cypress_ps2_read_cmd_status drivers/input/mouse/cypress_ps2.c:123
>>  [<ffffffff819e6b23>] cypress_send_ext_cmd+0x193/0x500
>> drivers/input/mouse/cypress_ps2.c:192
>>  [<ffffffff819e6f5a>] cypress_detect+0x2a/0xb0
>> drivers/input/mouse/cypress_ps2.c:208
>>  [<ffffffff819d5e66>] psmouse_extensions+0x1f6/0x4e0
>> drivers/input/mouse/psmouse-base.c:849 (discriminator 1)
>>  [<ffffffff819d63fd>] psmouse_switch_protocol+0x2ad/0x330
>> drivers/input/mouse/psmouse-base.c:1467
>>  [<ffffffff819d7426>] psmouse_connect+0x2e6/0x450
>> drivers/input/mouse/psmouse-base.c:1554 (discriminator 4)
>>  [<     inlined    >] serio_driver_probe+0x57/0x80
>> serio_connect_driver drivers/input/serio/serio.c:65
>>  [<ffffffff819bcf77>] serio_driver_probe+0x57/0x80
>> drivers/input/serio/serio.c:796
>>  [<     inlined    >] driver_probe_device+0x1da/0x460 really_probe
>> drivers/base/dd.c:308
>>  [<ffffffff81813b1a>] driver_probe_device+0x1da/0x460 drivers/base/dd.c:414
>>  [<ffffffff81813e64>] __driver_attach+0xc4/0xd0 drivers/base/dd.c:612
>>  [<ffffffff81810933>] bus_for_each_dev+0x93/0xe0 drivers/base/bus.c:314
>>  [<ffffffff81813353>] driver_attach+0x33/0x50 drivers/base/dd.c:631
>>  [<     inlined    >] serio_handle_event+0x2d3/0x3b0
>> serio_attach_driver drivers/input/serio/serio.c:826
>>  [<ffffffff819bd8e3>] serio_handle_event+0x2d3/0x3b0
>> drivers/input/serio/serio.c:245
>>  [<ffffffff810adcf9>] process_one_work+0x2a9/0x6d0 kernel/workqueue.c:2036
>>  [<ffffffff810aeddf>] worker_thread+0xbf/0x710 kernel/workqueue.c:2170
>>  [<ffffffff810b700c>] kthread+0x15c/0x180 kernel/kthread.c:207
>>  [<ffffffff81e71f5f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526
>> DBG: cpu = 0
>>
>> DBG: addr: ffff88019d703909
>> DBG: first offset: 1, second offset: 1
>> DBG: T1 clock: {T1: 17075020, T509: 142163}
>> DBG: T509 clock: {T509: 142167}
>> ==================================================================
>>
>> It seems that accessing 'psmouse->pktcnt' in
>> 'psmouse->packet[psmouse->pktcnt++] = data' in 'psmouse_interrupt()'
>> is racing with 'wait_event_timeout(ps2dev->wait, (psmouse->pktcnt >=
>> pktsize), msecs_to_jiffies(CYTP_CMD_TIMEOUT))' in
>> 'cypress_ps2_read_cmd_status()'.
>> If that's the case, it's possible that 'psmouse->pktcnt' is
>> incremented, but no data is written yet, so '(psmouse->pktcnt >=
>> pktsize)' will evaluate to true and the following 'memcpy' will access
>> invalid data.
>>
>> Could you confirm if this is a real data race?
>>
>> Thanks in advance!
>>
>
> Hi Andrey,
>
> I would like to ask you, did not you noticed some problem from Sanitizer
> with psmouse-base.c and alps.c code?
>
> There is unknown problem when alps.c receive invalid data from
> psmouse_interrupt/serio_interrupt/i8042_interrupt.
>
> And when I read your email with race condition & accesing invalid data
> in cypress driver. I'm thinking if there cannot be something like that.
>
> --
> Pali Rohár
> pali.rohar@...il.com
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