[syzbot] [net?] [usb?] KMSAN: uninit-value in lan78xx_reset

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c8bc81a52d5a Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1342fa62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=845da2a9c105a0be
dashboard link: https://syzkaller.appspot.com/bug?extid=62ec8226f01cb4ca19d9
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ec99afb47153/disk-c8bc81a5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b0879d84349c/vmlinux-c8bc81a5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9a55e2d5763/bzImage-c8bc81a5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+62ec82...@syzkaller.appspotmail.com

lan78xx 1-1:1.0 (unnamed net_device) (uninitialized): EEPROM is busy
=====================================================
BUG: KMSAN: uninit-value in lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1095 [inline]
BUG: KMSAN: uninit-value in lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline]
BUG: KMSAN: uninit-value in lan78xx_reset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241
lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1095 [inline]
lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline]
lan78xx_reset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241
lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766
lan78xx_probe+0x225c/0x3310 drivers/net/usb/lan78xx.c:4707
usb_probe_interface+0xd20/0x1460 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xdc0 drivers/base/dd.c:659
__driver_probe_device+0x268/0x380 drivers/base/dd.c:801
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:831
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:959
bus_for_each_drv+0x3e3/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1031
device_initial_probe+0x33/0x40 drivers/base/dd.c:1080
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3689
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+0x38d/0x690 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xdc0 drivers/base/dd.c:659
__driver_probe_device+0x268/0x380 drivers/base/dd.c:801
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:831
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:959
bus_for_each_drv+0x3e3/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1031
device_initial_probe+0x33/0x40 drivers/base/dd.c:1080
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3689
usb_new_device+0x1062/0x20f0 drivers/usb/core/hub.c:2694
hub_port_connect drivers/usb/core/hub.c:5566 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
port_event drivers/usb/core/hub.c:5870 [inline]
hub_event+0x54e0/0x7620 drivers/usb/core/hub.c:5952
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xb8e/0x1d80 kernel/workqueue.c:3319
worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
kthread+0xd59/0xf00 kernel/kthread.c:463
ret_from_fork+0x1e3/0x310 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Local variable sig.i.i created at:
lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1092 [inline]
lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline]
lan78xx_reset+0x77e/0x2cd0 drivers/net/usb/lan78xx.c:3241
lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766

CPU: 1 UID: 0 PID: 7482 Comm: kworker/1:6 Tainted: G W syzkaller #0 PREEMPT(none)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: usb_hub_wq hub_event
=====================================================


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