usb/serial/visor: slab-out-of-bounds in palm_os_3_probe

[Andrey Konovalov]

Hi!

I've got the following report while fuzzing the kernel with syzkaller.

On commit dc972a67cc54585bd83ad811c4e9b6ab3dcd427e (4.14-rc2+).

There's no check on the connection_info->num_ports value when
iterating over ports.

usb 1-1: Handspring Visor / Palm OS: port 162, is for unknown use
usb 1-1: Handspring Visor / Palm OS: port 81, is for unknown use
==================================================================
BUG: KASAN: slab-out-of-bounds in palm_os_3_probe+0x4e4/0x570
Read of size 1 at addr ffff8800686daa26 by task kworker/0:1/24

CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.14.0-rc2-42748-gcd3da2fe6c25 #324
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x292/0x395 lib/dump_stack.c:52
 print_address_description+0x78/0x280 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351
 kasan_report+0x23d/0x350 mm/kasan/report.c:409
 __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:427
 palm_os_3_probe+0x4e4/0x570 drivers/usb/serial/visor.c:348
 visor_probe+0x11c/0x1e0 drivers/usb/serial/visor.c:463
 usb_serial_probe+0x540/0x4090 drivers/usb/serial/usb-serial.c:903
 usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
 __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
 device_add+0xd0b/0x1660 drivers/base/core.c:1835
 usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
 generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
 usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
 __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
 device_add+0xd0b/0x1660 drivers/base/core.c:1835
 usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2538
 hub_port_connect drivers/usb/core/hub.c:4984
 hub_port_connect_change drivers/usb/core/hub.c:5090
 port_event drivers/usb/core/hub.c:5196
 hub_event_impl+0x1971/0x3760 drivers/usb/core/hub.c:5310
 hub_event+0x11b/0x3f0 drivers/usb/core/hub.c:5206
 process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
 worker_thread+0x221/0x1850 kernel/workqueue.c:2253
 kthread+0x3a1/0x470 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Allocated by task 24:
 save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x11e/0x2d0 mm/slub.c:2772
 kmalloc ./include/linux/slab.h:493
 palm_os_3_probe+0x7c/0x570 drivers/usb/serial/visor.c:325
 visor_probe+0x11c/0x1e0 drivers/usb/serial/visor.c:463
 usb_serial_probe+0x540/0x4090 drivers/usb/serial/usb-serial.c:903
 usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
 __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
 device_add+0xd0b/0x1660 drivers/base/core.c:1835
 usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
 generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
 usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
 __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
 device_add+0xd0b/0x1660 drivers/base/core.c:1835
 usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2538
 hub_port_connect drivers/usb/core/hub.c:4984
 hub_port_connect_change drivers/usb/core/hub.c:5090
 port_event drivers/usb/core/hub.c:5196
 hub_event_impl+0x1971/0x3760 drivers/usb/core/hub.c:5310
 hub_event+0x11b/0x3f0 drivers/usb/core/hub.c:5206
 process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
 worker_thread+0x221/0x1850 kernel/workqueue.c:2253
 kthread+0x3a1/0x470 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Freed by task 2772:
 save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459
 kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524
 slab_free_hook mm/slub.c:1390
 slab_free_freelist_hook mm/slub.c:1412
 slab_free mm/slub.c:2988
 kfree+0xf6/0x2f0 mm/slub.c:3919
 signalfd_release+0x3c/0x50 fs/signalfd.c:56
 __fput+0x33e/0x800 fs/file_table.c:210
 ____fput+0x1a/0x20 fs/file_table.c:244
 task_work_run+0x1af/0x280 kernel/task_work.c:112
 tracehook_notify_resume ./include/linux/tracehook.h:191
 exit_to_usermode_loop+0x1d4/0x210 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197
 syscall_return_slowpath+0x3e2/0x4a0 arch/x86/entry/common.c:266
 entry_SYSCALL_64_fastpath+0xc0/0xc2 arch/x86/entry/entry_64.S:238

The buggy address belongs to the object at ffff8800686daa20
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 6 bytes inside of
 8-byte region [ffff8800686daa20, ffff8800686daa28)
The buggy address belongs to the page:
page:ffffea0001a1b680 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x100000000000100(slab)
raw: 0100000000000100 0000000000000000 0000000000000000 0000000180aa00aa
raw: ffffea00018f6e80 0000000500000005 ffff88006c403c80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8800686da900: fb fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb
 ffff8800686da980: fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb fc
>ffff8800686daa00: fc fb fc fc 06 fc fc fb fc fc fb fc fc fb fc fc
                               ^
 ffff8800686daa80: fb fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb
 ffff8800686dab00: fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb fc
==================================================================