[BUG] WARNING in i2c_mux_add_adapter

[Farhad Alemi]

Hello,

As part of the kernel research at ASU's SEFCOM
lab, we hit the crash below. Crash reports can be found here:

  https://github.com/farhad-alemi/public_bug_reports/tree/main/185-warning-in-i2c-mux-add-adapter/

  can't create symlink to channel 0
  WARNING: drivers/i2c/i2c-mux.c:403 at
i2c_mux_add_adapter+0xcd8/0xeb0 drivers/i2c/i2c-mux.c:401, CPU#0:
syz.1.250/13052
  RIP: 0010:i2c_mux_add_adapter+0xcdc/0xeb0 drivers/i2c/i2c-mux.c:401
  Call Trace:
   i2c_mux_add_adapter+0xcdc/0xeb0 drivers/i2c/i2c-mux.c:401
   cx231xx_dev_init+0x2fb/0x1260 drivers/media/usb/cx231xx/cx231xx-core.c:1334
   cx231xx_init_dev drivers/media/usb/cx231xx/cx231xx-cards.c:1450 [inline]
   cx231xx_usb_probe+0xc48/0x2140 drivers/media/usb/cx231xx/cx231xx-cards.c:1819
   usb_probe_interface+0x657/0xc70 drivers/usb/core/driver.c:396
   really_probe+0x267/0xaf0 drivers/base/dd.c:709
   device_driver_attach+0xdc/0x1d0 drivers/base/dd.c:1206
   bind_store+0x1d0/0x220 drivers/base/bus.c:267
   kernfs_fop_write_iter+0x2fa/0x480 fs/kernfs/file.c:352

Our reproducer.c is available upon request.

Happy to test a patch if that would help.

Regards,