KMSAN: uninit-value in smsc95xx_reset

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ce8056d1 wip: changed copy_from_user where instrumented
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1496679e900000
kernel config: https://syzkaller.appspot.com/x/.config?x=3afe005fb99591f
dashboard link: https://syzkaller.appspot.com/bug?extid=c74c24b43c9ae534f0e0
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d8cc86900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=117e8fbe900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c74c24...@syzkaller.appspotmail.com

smsc95xx 1-1:1.0 (unnamed net_device) (uninitialized): Failed to read reg index 0x00000030: -32
smsc95xx 1-1:1.0 (unnamed net_device) (uninitialized): Error reading E2P_CMD
=====================================================
BUG: KMSAN: uninit-value in smsc95xx_reset+0x353/0x3eb0 drivers/net/usb/smsc95xx.c:1039
CPU: 1 PID: 27 Comm: kworker/1:1 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x21c/0x280 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
smsc95xx_reset+0x353/0x3eb0 drivers/net/usb/smsc95xx.c:1039
smsc95xx_bind+0x8b3/0x1720 drivers/net/usb/smsc95xx.c:1289
usbnet_probe+0x1152/0x3f90 drivers/net/usb/usbnet.c:1737
usb_probe_interface+0xece/0x1550 drivers/usb/core/driver.c:374
really_probe+0xf20/0x20b0 drivers/base/dd.c:529
driver_probe_device+0x293/0x390 drivers/base/dd.c:701
__device_attach_driver+0x63f/0x830 drivers/base/dd.c:807
bus_for_each_drv+0x2ca/0x3f0 drivers/base/bus.c:431
__device_attach+0x4e2/0x7f0 drivers/base/dd.c:873
device_initial_probe+0x4a/0x60 drivers/base/dd.c:920
bus_probe_device+0x177/0x3d0 drivers/base/bus.c:491
device_add+0x3b0e/0x40d0 drivers/base/core.c:2680
usb_set_configuration+0x380f/0x3f10 drivers/usb/core/message.c:2032
usb_generic_driver_probe+0x138/0x300 drivers/usb/core/generic.c:241
usb_probe_device+0x311/0x490 drivers/usb/core/driver.c:272



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