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Date:   Tue, 16 May 2023 16:36:24 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
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>
Subject: Re: [BUG][NEW DATA] Kmemleak, possibly hiddev_connect(), in 6.3.0+
 torvalds tree commit gfc4354c6e5c2
Message-ID: <2023051607-sturdy-jiffy-ca99@gregkh>
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>
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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);