linux-kernel - Re: [syzbot] [hwmon?] KMSAN: uninit-value in get_temp

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Message-ID: <fe5fe144dea8665f96b943e9abe58fc8be536d69.camel@mariuszachmann.de>
Date: Thu, 19 Jun 2025 10:01:21 +0200
From: Marius Zachmann <mail@...iuszachmann.de>
To: Guenter Roeck <linux@...ck-us.net>, syzbot	
 <syzbot+3bbbade4e1a7ab45ca3b@...kaller.appspotmail.com>, jdelvare@...e.com,
 	linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [hwmon?] KMSAN: uninit-value in get_temp_cnct

Am Mittwoch, dem 18.06.2025 um 22:56 -0700 schrieb Guenter Roeck:
> On 6/18/25 21:31, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    4774cfe3543a Merge tag 'scsi-fixes' of
> > git://git.kernel.or..
> > git tree:       upstream
> > console output:
> > https://syzkaller.appspot.com/x/log.txt?x=10e3f10c580000
> > kernel config: 
> > https://syzkaller.appspot.com/x/.config?x=61539536677af51c
> > dashboard link:
> > https://syzkaller.appspot.com/bug?extid=3bbbade4e1a7ab45ca3b
> > compiler:       Debian clang version 20.1.6
> > (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian
> > LLD 20.1.6
> > userspace arch: i386
> > 
> > Unfortunately, I don't have any reproducer for this issue yet.
> > 
> 
> It doesn't need one: The problem will be seen if the data returned
> from the
> power supply is shorter than expected. In the example below, the
> problem will
> be seen if less than NUM_TEMP_SENSORS+1 data bytes were received.
> One possible fix would be to record the returned data length in
> ccp_raw_event()
> and to have each caller of send_usb_cmd() check if the returned
> amount of data
> is sufficient.
> 
> Guenter

The device should always return the same number of bytes.
I could zero-initialize the buffer at allocation. Then there should
be no uninitialized values.
Also I could check the number of returned bytes in send_usb_cmd()
instead of having each caller checking it, and return -EIO if
it is not correct?

Marius

> 
> > Downloadable assets:
> > disk image:
> > https://storage.googleapis.com/syzbot-assets/0cb38ba04f99/disk-4774cfe3.raw.xz
> > vmlinux:
> > https://storage.googleapis.com/syzbot-assets/ff376a7ba200/vmlinux-4774cfe3.xz
> > kernel image:
> > https://storage.googleapis.com/syzbot-assets/570051315dbf/bzImage-4774cfe3.xz
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to
> > the commit:
> > Reported-by: syzbot+3bbbade4e1a7ab45ca3b@...kaller.appspotmail.com
> > 
> > usb 7-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> > usb 7-1: config 0 descriptor??
> > corsair-cpro 0003:1B1C:0C10.0017: hidraw0: USB HID v4.06 Device
> > [HID 1b1c:0c10] on usb-dummy_hcd.6-1/input0
> > =====================================================
> > BUG: KMSAN: uninit-value in get_temp_cnct+0x1f3/0x3b0
> > drivers/hwmon/corsair-cpro.c:497
> >   get_temp_cnct+0x1f3/0x3b0 drivers/hwmon/corsair-cpro.c:497
> >   ccp_probe+0x458/0x790 drivers/hwmon/corsair-cpro.c:622
> >   __hid_device_probe drivers/hid/hid-core.c:2724 [inline]
> >   hid_device_probe+0x539/0xab0 drivers/hid/hid-core.c:2761
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   hid_add_device+0x5ed/0x7b0 drivers/hid/hid-core.c:2907
> >   usbhid_probe+0x1fec/0x2660 drivers/hid/usbhid/hid-core.c:1435
> >   usb_probe_interface+0xd04/0x1310 drivers/usb/core/driver.c:396
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   usb_set_configuration+0x3493/0x3b70
> > drivers/usb/core/message.c:2210
> >   usb_generic_driver_probe+0xfc/0x290
> > drivers/usb/core/generic.c:250
> >   usb_probe_device+0x38a/0x690 drivers/usb/core/driver.c:291
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   usb_new_device+0x104b/0x20c0 drivers/usb/core/hub.c:2663
> >   hub_port_connect drivers/usb/core/hub.c:5535 [inline]
> >   hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
> >   port_event drivers/usb/core/hub.c:5835 [inline]
> >   hub_event+0x5588/0x7580 drivers/usb/core/hub.c:5917
> >   process_one_work kernel/workqueue.c:3238 [inline]
> >   process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
> >   worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
> >   kthread+0xd5c/0xf00 kernel/kthread.c:464
> >   ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
> >   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> > 
> > Uninit was stored to memory at:
> >   get_temp_cnct+0x1ec/0x3b0 drivers/hwmon/corsair-cpro.c:496
> >   ccp_probe+0x458/0x790 drivers/hwmon/corsair-cpro.c:622
> >   __hid_device_probe drivers/hid/hid-core.c:2724 [inline]
> >   hid_device_probe+0x539/0xab0 drivers/hid/hid-core.c:2761
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   hid_add_device+0x5ed/0x7b0 drivers/hid/hid-core.c:2907
> >   usbhid_probe+0x1fec/0x2660 drivers/hid/usbhid/hid-core.c:1435
> >   usb_probe_interface+0xd04/0x1310 drivers/usb/core/driver.c:396
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   usb_set_configuration+0x3493/0x3b70
> > drivers/usb/core/message.c:2210
> >   usb_generic_driver_probe+0xfc/0x290
> > drivers/usb/core/generic.c:250
> >   usb_probe_device+0x38a/0x690 drivers/usb/core/driver.c:291
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   usb_new_device+0x104b/0x20c0 drivers/usb/core/hub.c:2663
> >   hub_port_connect drivers/usb/core/hub.c:5535 [inline]
> >   hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
> >   port_event drivers/usb/core/hub.c:5835 [inline]
> >   hub_event+0x5588/0x7580 drivers/usb/core/hub.c:5917
> >   process_one_work kernel/workqueue.c:3238 [inline]
> >   process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
> >   worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
> >   kthread+0xd5c/0xf00 kernel/kthread.c:464
> >   ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
> >   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> > 
> > Uninit was created at:
> >   slab_post_alloc_hook mm/slub.c:4154 [inline]
> >   slab_alloc_node mm/slub.c:4197 [inline]
> >   __do_kmalloc_node mm/slub.c:4327 [inline]
> >   __kmalloc_node_track_caller_noprof+0x96d/0x12f0 mm/slub.c:4347
> >   alloc_dr drivers/base/devres.c:119 [inline]
> >   devm_kmalloc+0xd7/0x2f0 drivers/base/devres.c:864
> >   ccp_probe+0x114/0x790 drivers/hwmon/corsair-cpro.c:596
> >   __hid_device_probe drivers/hid/hid-core.c:2724 [inline]
> >   hid_device_probe+0x539/0xab0 drivers/hid/hid-core.c:2761
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   hid_add_device+0x5ed/0x7b0 drivers/hid/hid-core.c:2907
> >   usbhid_probe+0x1fec/0x2660 drivers/hid/usbhid/hid-core.c:1435
> >   usb_probe_interface+0xd04/0x1310 drivers/usb/core/driver.c:396
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   usb_set_configuration+0x3493/0x3b70
> > drivers/usb/core/message.c:2210
> >   usb_generic_driver_probe+0xfc/0x290
> > drivers/usb/core/generic.c:250
> >   usb_probe_device+0x38a/0x690 drivers/usb/core/driver.c:291
> >   call_driver_probe drivers/base/dd.c:-1 [inline]
> >   really_probe+0x4d4/0xd90 drivers/base/dd.c:657
> >   __driver_probe_device+0x268/0x380 drivers/base/dd.c:799
> >   driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
> >   __device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
> >   bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
> >   __device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
> >   device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
> >   bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
> >   device_add+0x12a9/0x1c10 drivers/base/core.c:3692
> >   usb_new_device+0x104b/0x20c0 drivers/usb/core/hub.c:2663
> >   hub_port_connect drivers/usb/core/hub.c:5535 [inline]
> >   hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
> >   port_event drivers/usb/core/hub.c:5835 [inline]
> >   hub_event+0x5588/0x7580 drivers/usb/core/hub.c:5917
> >   process_one_work kernel/workqueue.c:3238 [inline]
> >   process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
> >   worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
> >   kthread+0xd5c/0xf00 kernel/kthread.c:464
> >   ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
> >   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> > 
> > CPU: 0 UID: 0 PID: 5855 Comm: kworker/0:3 Not tainted 6.16.0-rc1-
> > syzkaller-00203-g4774cfe3543a #0 PREEMPT(undef)
> > Hardware name: Google Google Compute Engine/Google Compute Engine,
> > BIOS Google 05/07/2025
> > Workqueue: usb_hub_wq hub_event
> > =====================================================
> > 
> > 
> > ---
> > This report 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@...glegroups.com.
> > 
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > 
> > If the report is already addressed, let syzbot know by replying
> > with:
> > #syz fix: exact-commit-title
> > 
> > If you want to overwrite report's subsystems, reply with:
> > #syz set subsystems: new-subsystem
> > (See the list of subsystem names on the web dashboard)
> > 
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
> > 
> > If you want to undo deduplication, reply with:
> > #syz undup