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Message-ID: <c3ed934f-b749-c9ce-bf4c-ec46bc5d44d7@alu.unizg.hr>
Date:   Wed, 17 May 2023 21:41:38 +0200
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Subject: Re: [BUG][NEW DATA] Kmemleak, possibly hiddev_connect(), in 6.3.0+
 torvalds tree commit gfc4354c6e5c2
Content-Language: en-US
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Mirsad Goran Todorovac <mirsad.goran.todorovac@alu.hr>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-input@vger.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Jiri Kosina <jikos@kernel.org>
References: <f64b17fa-d509-ad30-6e8d-e4c979818047@alu.unizg.hr>
 <2023050824-juiciness-catching-9290@gregkh>
 <2023050854-collage-dreamt-660c@gregkh>
 <c73471aa-522a-83a4-5614-506581604301@alu.unizg.hr>
 <2023050958-precut-vividly-94bf@gregkh>
 <987f9008-7eac-e2a4-31f6-8479f0e4a626@alu.unizg.hr>
 <2023051607-sturdy-jiffy-ca99@gregkh>
 <70dd7fa2-9a5f-9361-ebe0-bb337c523d09@alu.unizg.hr>
 <2023051704-basket-hardcover-1a0c@gregkh>
From:   Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
In-Reply-To: <2023051704-basket-hardcover-1a0c@gregkh>
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On 5/17/23 20:57, Greg Kroah-Hartman wrote:
> On Wed, May 17, 2023 at 06:10:54PM +0200, Mirsad Goran Todorovac wrote:
>> On 5/16/23 16:36, Greg Kroah-Hartman wrote:
>>> On Fri, May 12, 2023 at 11:33:31PM +0200, Mirsad Goran Todorovac wrote:
>>>> Hi,
>>>>
>>>> On 5/9/23 04:59, Greg Kroah-Hartman wrote:
>>>>> On Tue, May 09, 2023 at 01:51:35AM +0200, Mirsad Goran Todorovac wrote:
>>>>>>
>>>>>>
>>>>>> On 08. 05. 2023. 16:01, Greg Kroah-Hartman wrote:
>>>>>>> On Mon, May 08, 2023 at 08:51:55AM +0200, Greg Kroah-Hartman wrote:
>>>>>>>> On Mon, May 08, 2023 at 08:30:07AM +0200, Mirsad Goran Todorovac wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> There seems to be a kernel memory leak in the USB keyboard driver.
>>>>>>>>>
>>>>>>>>> The leaked memory allocs are 96 and 512 bytes.
>>>>>>>>>
>>>>>>>>> The platform is Ubuntu 22.04 LTS on a assembled AMD Ryzen 9 with X670E PG
>>>>>>>>> Lightning mobo,
>>>>>>>>> and Genius SlimStar i220 GK-080012 keyboard.
>>>>>>>>>
>>>>>>>>> (Logitech M100 HID mouse is not affected by the bug.)
>>>>>>>>>
>>>>>>>>> BIOS is:
>>>>>>>>>
>>>>>>>>>          *-firmware
>>>>>>>>>               description: BIOS
>>>>>>>>>               vendor: American Megatrends International, LLC.
>>>>>>>>>               physical id: 0
>>>>>>>>>               version: 1.21
>>>>>>>>>               date: 04/26/2023
>>>>>>>>>               size: 64KiB
>>>>>>>>>
>>>>>>>>> The kernel is 6.3.0-torvalds-<id>-13466-gfc4354c6e5c2.
>>>>>>>>>
>>>>>>>>> The keyboard is recognised as Chicony:
>>>>>>>>>
>>>>>>>>>                      *-usb
>>>>>>>>>                           description: Keyboard
>>>>>>>>>                           product: CHICONY USB Keyboard
>>>>>>>>>                           vendor: CHICONY
>>>>>>>>>                           physical id: 2
>>>>>>>>>                           bus info: usb@5:2
>>>>>>>>>                           logical name: input35
>>>>>>>>>                           logical name: /dev/input/event4
>>>>>>>>>                           logical name: input35::capslock
>>>>>>>>>                           logical name: input35::numlock
>>>>>>>>>                           logical name: input35::scrolllock
>>>>>>>>>                           logical name: input36
>>>>>>>>>                           logical name: /dev/input/event5
>>>>>>>>>                           logical name: input37
>>>>>>>>>                           logical name: /dev/input/event6
>>>>>>>>>                           logical name: input38
>>>>>>>>>                           logical name: /dev/input/event8
>>>>>>>>>                           version: 2.30
>>>>>>>>>                           capabilities: usb-2.00 usb
>>>>>>>>>                           configuration: driver=usbhid maxpower=100mA
>>>>>>>>> speed=1Mbit/s
>>>>>>>>>
>>>>>>>>> The bug is easily reproduced by unplugging the USB keyboard, waiting about a
>>>>>>>>> couple of seconds,
>>>>>>>>> and then reconnect and scan for memory leaks twice.
>>>>>>>>>
>>>>>>>>> The kmemleak log is as follows [edited privacy info]:
>>>>>>>>>
>>>>>>>>> root@hostname:/home/username# cat /sys/kernel/debug/kmemleak
>>>>>>>>> unreferenced object 0xffff8dd020037c00 (size 96):
>>>>>>>>>       comm "systemd-udevd", pid 435, jiffies 4294892550 (age 8909.356s)
>>>>>>>>>       hex dump (first 32 bytes):
>>>>>>>>>         5d 8e 4e b9 ff ff ff ff 00 00 00 00 00 00 00 00 ].N.............
>>>>>>>>>         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
>>>>>>>>>       backtrace:
>>>>>>>>>         [<ffffffffb81a74be>] __kmem_cache_alloc_node+0x22e/0x2b0
>>>>>>>>>         [<ffffffffb8127b6e>] kmalloc_trace+0x2e/0xa0
>>>>>>>>>         [<ffffffffb87543d9>] class_create+0x29/0x80
>>>>>>>>>         [<ffffffffb8880d24>] usb_register_dev+0x1d4/0x2e0
>>>>>>>>
>>>>>>>> As the call to class_create() in this path is now gone in 6.4-rc1, can
>>>>>>>> you retry that release to see if this is still there or not?
>>>>>>>
>>>>>>> No, wait, it's still there, I was looking at a development branch of
>>>>>>> mine that isn't sent upstream yet.  And syzbot just reported the same
>>>>>>> thing:
>>>>>>> 	https://lore.kernel.org/r/00000000000058d15f05fb264013@google.com
>>>>>>>
>>>>>>> So something's wrong here, let me dig into it tomorrow when I get a
>>>>>>> chance...
>>>>>>
>>>>>> If this could help, here is the bisect of the bug (I could not discern what
>>>>>> could possibly be wrong):
>>>>>>
>>>>>> user@host:~/linux/kernel/linux_torvalds$ git bisect log
>>>>>> git bisect start
>>>>>> # bad: [ac9a78681b921877518763ba0e89202254349d1b] Linux 6.4-rc1
>>>>>> git bisect bad ac9a78681b921877518763ba0e89202254349d1b
>>>>>> # good: [c9c3395d5e3dcc6daee66c6908354d47bf98cb0c] Linux 6.2
>>>>>> git bisect good c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
>>>>>> # good: [85496c9b3bf8dbe15e2433d3a0197954d323cadc] Merge branch
>>>>>> 'net-remove-some-rcu_bh-cruft'
>>>>>> git bisect good 85496c9b3bf8dbe15e2433d3a0197954d323cadc
>>>>>> # good: [b68ee1c6131c540a62ecd443be89c406401df091] Merge tag 'scsi-misc' of
>>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
>>>>>> git bisect good b68ee1c6131c540a62ecd443be89c406401df091
>>>>>> # bad: [888d3c9f7f3ae44101a3fd76528d3dd6f96e9fd0] Merge tag 'sysctl-6.4-rc1'
>>>>>> of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
>>>>>> git bisect bad 888d3c9f7f3ae44101a3fd76528d3dd6f96e9fd0
>>>>>> # good: [34b62f186db9614e55d021f8c58d22fc44c57911] Merge tag
>>>>>> 'pci-v6.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci
>>>>>> git bisect good 34b62f186db9614e55d021f8c58d22fc44c57911
>>>>>> # good: [34da76dca4673ab1819830b4924bb5b436325b26] Merge tag
>>>>>> 'for-linus-2023042601' of
>>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid
>>>>>> git bisect good 34da76dca4673ab1819830b4924bb5b436325b26
>>>>>> # good: [97b2ff294381d05e59294a931c4db55276470cb5] Merge tag
>>>>>> 'staging-6.4-rc1' of
>>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
>>>>>> git bisect good 97b2ff294381d05e59294a931c4db55276470cb5
>>>>>> # good: [2025b2ca8004c04861903d076c67a73a0ec6dfca] mcb-lpc: Reallocate
>>>>>> memory region to avoid memory overlapping
>>>>>> git bisect good 2025b2ca8004c04861903d076c67a73a0ec6dfca
>>>>>> # bad: [d06f5a3f7140921ada47d49574ae6fa4de5e2a89] cdx: fix build failure due
>>>>>> to sysfs 'bus_type' argument needing to be const
>>>>>> git bisect bad d06f5a3f7140921ada47d49574ae6fa4de5e2a89
>>>>>> # good: [dcfbb67e48a2becfce7990386e985b9c45098ee5] driver core: class: use
>>>>>> lock_class_key already present in struct subsys_private
>>>>>> git bisect good dcfbb67e48a2becfce7990386e985b9c45098ee5
>>>>>> # bad: [6f14c02220c791d5c46b0f965b9340c58f3d503d] driver core: create
>>>>>> class_is_registered()
>>>>>> git bisect bad 6f14c02220c791d5c46b0f965b9340c58f3d503d
>>>>>> # good: [2f9e87f5a2941b259336c7ea6c5a1499ede4554a] driver core: Add a
>>>>>> comment to set_primary_fwnode() on nullifying
>>>>>> git bisect good 2f9e87f5a2941b259336c7ea6c5a1499ede4554a
>>>>>> # bad: [02fe26f25325b547b7a31a65deb0326c04bb5174] firmware_loader: Add debug
>>>>>> message with checksum for FW file
>>>>>> git bisect bad 02fe26f25325b547b7a31a65deb0326c04bb5174
>>>>>> # good: [884f8ce42ccec9d0bf11d8bf9f111e5961ca1c82] driver core: class:
>>>>>> implement class_get/put without the private pointer.
>>>>>> git bisect good 884f8ce42ccec9d0bf11d8bf9f111e5961ca1c82
>>>>>> # bad: [3f84aa5ec052dba960baca4ab8a352d43d47028e] base: soc: populate
>>>>>> machine name in soc_device_register if empty
>>>>>> git bisect bad 3f84aa5ec052dba960baca4ab8a352d43d47028e
>>>>>> # bad: [7b884b7f24b42fa25e92ed724ad82f137610afaf] driver core: class.c:
>>>>>> convert to only use class_to_subsys
>>>>>> git bisect bad 7b884b7f24b42fa25e92ed724ad82f137610afaf
>>>>>> # first bad commit: [7b884b7f24b42fa25e92ed724ad82f137610afaf] driver core:
>>>>>> class.c: convert to only use class_to_subsys
>>>>>> user@host:~/linux/kernel/linux_torvalds$
>>>>>
>>>>> This helps a lot, thanks.  I got the reference counting wrong somewhere
>>>>> in here, I thought I tested this better, odd it shows up now...
>>>>>
>>>>> I'll try to work on it this week.
>>>>
>>>> I have figured out that the leak occurs on keyboard unplugging only, one
>>>> or two leaks (maybe a race condition?).
>>>>
>>>> Please NOTE that the number of leaks is now odd:
>>>>
>>>> root@defiant:/home/marvin# cat /sys/kernel/debug/kmemleak | grep comm
>>>>     comm "systemd-udevd", pid 330, jiffies 4294892588 (age 715.772s)
>>>>     comm "systemd-udevd", pid 330, jiffies 4294892588 (age 715.772s)
>>>>     comm "kworker/6:0", pid 54, jiffies 4294907989 (age 654.224s)
>>>>     comm "kworker/6:0", pid 54, jiffies 4294907989 (age 654.272s)
>>>>     comm "kworker/6:3", pid 3046, jiffies 4294935362 (age 544.780s)
>>>>     comm "kworker/6:0", pid 54, jiffies 4294964122 (age 429.740s)
>>>>     comm "kworker/6:0", pid 54, jiffies 4294964122 (age 429.784s)
>>>> root@defiant:/home/marvin#
>>>>
>>>> At one time unplugging keyboard generated only one leak, but only at one
>>>> time. As it requires manually unplugging keyboard, I didn't seem to find a
>>>> way to automate it, but it doesn't seem to require root access.
>>>>
>>>> BTW, I've seen in syzbot output that kmemleak output has debug source file
>>>> names and line numbers. I couldn't make that work with the dbg .deb.
>>>>
>>>> I will do some more homework, but this was a rough week.
>>>
>>> I made up a patch based on code inspection alone, as I couldn't
>>> reproduce this locally at all:
>>> 	https://lore.kernel.org/r/2023051628-thumb-boaster-5680@gregkh
>>> and it seemed to pass syzbot's tests.
>>>
>>> I've included it here below, can you test it as well?
>>>
>>> Hm, I only tested with a USB mouse unplug/plug cycle, maybe the issue is
>>> a keyboard?
>>>
>>> thanks,
>>>
>>> greg k-h
>>>
>>> -------------
>>>
>>> diff --git a/drivers/base/class.c b/drivers/base/class.c
>>> index ac1808d1a2e8..9b44edc8416f 100644
>>> --- a/drivers/base/class.c
>>> +++ b/drivers/base/class.c
>>> @@ -320,6 +322,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
>>>    		start_knode = &start->p->knode_class;
>>>    	klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
>>>    	iter->type = type;
>>> +	iter->sp = sp;
>>>    }
>>>    EXPORT_SYMBOL_GPL(class_dev_iter_init);
>>> @@ -361,6 +364,7 @@ EXPORT_SYMBOL_GPL(class_dev_iter_next);
>>>    void class_dev_iter_exit(struct class_dev_iter *iter)
>>>    {
>>>    	klist_iter_exit(&iter->ki);
>>> +	subsys_put(iter->sp);
>>>    }
>>>    EXPORT_SYMBOL_GPL(class_dev_iter_exit);
>>> diff --git a/include/linux/device/class.h b/include/linux/device/class.h
>>> index 9deeaeb457bb..abf3d3bfb6fe 100644
>>> --- a/include/linux/device/class.h
>>> +++ b/include/linux/device/class.h
>>> @@ -74,6 +74,7 @@ struct class {
>>>    struct class_dev_iter {
>>>    	struct klist_iter		ki;
>>>    	const struct device_type	*type;
>>> +	struct subsys_private		*sp;
>>>    };
>>>    int __must_check class_register(const struct class *class);
>>
>> The build with the latest 6.4-rc2 and without this patch still leaked,
>> the build with the same commit and this patch applied was successful:
>>
>> root@defiant:/home/marvin# cat /sys/kernel/debug/kmemleak
>> root@defiant:/home/marvin#
>>
>> Tried three times, and it is a OK.
>>
>> Congratulations! This had fixed the leak.
> 
> Wonderful, thanks for testing, can I add your "Tested-by:" to it?

Don't mention it. Tested-by: is fine, certainly.

>> I wonder why it didn't show in the other contexts, hardware and archs?
> 
> It might depend on your keyboard if it has other things on it?  I don't
> know, sorry, I didn't spend much time digging after I found the "obvious
> leak" based on the bisection you provided, which was very very helpful,
> thanks for that.

It looks like a rather normal Genius keyboard, which the system detected
as "Chicony".

Maybe it is the motherboard or the controller? Did I send the lshw.txt?

Yes, I did.

I can't tell which one of these it is:

root@defiant:/home/marvin# lspci -k | grep -B2 xhci
15:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] Device 43f7 
(rev 01)
	Subsystem: ASMedia Technology Inc. Device 1142
	Kernel driver in use: xhci_hcd
	Kernel modules: xhci_pci
--
17:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] Device 43f7 
(rev 01)
	Subsystem: ASMedia Technology Inc. Device 1142
	Kernel driver in use: xhci_hcd
	Kernel modules: xhci_pci
--
1a:00.3 USB controller: Advanced Micro Devices, Inc. [AMD] Device 15b6
	Subsystem: ASRock Incorporation Device 15b6
	Kernel driver in use: xhci_hcd
	Kernel modules: xhci_pci
1a:00.4 USB controller: Advanced Micro Devices, Inc. [AMD] Device 15b7
	Subsystem: ASRock Incorporation Device 15b6
	Kernel driver in use: xhci_hcd
	Kernel modules: xhci_pci
--
1b:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] Device 15b8
	Subsystem: ASRock Incorporation Device 15b6
	Kernel driver in use: xhci_hcd
	Kernel modules: xhci_pci
root@defiant:/home/marvin#

Regarding the bisection, no need to thank, I was actually happy to test
the new hardware.

Before, it would take 15 hours for the bisect that big.

Though the box was slightly overheating (91 °C), and probably there
ought to be a way to recompile only changed sources after a
"git checkout" ... that would speed up many bisects, BTW.

> And leaks are hard to notice, especially ones that only show up when you
> remove a specific type of device.

Well, the leaks are rather harmless, but they show some inconsistency in
the code, so I took them seriously.

> thanks again for your help here,

Not at all, I hope to find some "real" bugs. :-)

> greg k-h

Best regards,
Mirsad