[BUG] ci_hdrc_add_device -- KASAN slab-out-of-bounds reading a FOREIGN device's platform_data

[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/150-usb-chipidea-foreign-platform_data-oob/

  BUG: KASAN: slab-out-of-bounds in ci_hdrc_add_device+0xb76/0xd10
  Read of size 4 at addr ffff88810e9061c8 by task repro/9505
  Call Trace:
   ci_hdrc_add_device+0xb76/0xd10
   ci_hdrc_usb2_probe+0x22d/0x370
   platform_probe+0xf9/0x190
   really_probe+0x267/0xaf0
   __driver_probe_device+0x1e2/0x350
   device_driver_attach+0xe0/0x1d0
   bind_store+0x1d0/0x220
   kernfs_fop_write_iter+0x3af/0x540
   vfs_write+0x61d/0xb90
   ksys_write+0x150/0x270

Our reproducer.c is available upon request.

Happy to test a patch if that would help.

Regards,