Re: BUG: KASAN: use-after-free in xhci_trb_virt_to_dma.part.24+0x1c/0x80

[Mathias Nyman]

On 28.01.2018 23:43, Paul Menzel wrote:
> Dear Linux folks,
>
>
> Using Linux 4.15-rc9+ with KASAN enabled on the TUXEDO Book 1406, playing with Bluetooth â disabling a device â I was able to trigger the warning below.

Thanks, first guess is that btusb calls usb_set_interface() with URBs still scheduled for a endpoint.
So something like this happens:

btusb_work [btusb]
  usb_set_interface
    usb_hcd_alloc_bandwidth
      xhci_check_bandwidth
         xhci_free_endpoint_ring   -> frees xhci endpoint ring.
    usb_disable_interface
      usb_disable_endpoint
        usb_hcd_flush_endpoint
          unlink1
            xhci_urb_dequeue       -> tries to access xhci endpoint ring in URB

description for usb_set_interface() says:
* This call is synchronous, and may not be used in an interrupt context.
* Also, drivers must not change altsettings while urbs are scheduled for
* endpoints in that interface; all such urbs must first be completed
* (perhaps forced by unlinking).

Adding some bluetooth people

-Mathias


> > [ 7384.326627] ==================================================================
> > [ 7384.326644] BUG: KASAN: use-after-free in xhci_trb_virt_to_dma.part.24+0x1c/0x80
> > [ 7384.326652] Read of size 8 at addr ffff88068c491c00 by task kworker/0:3/17280
> >
> > [ 7384.326669] CPU: 0 PID: 17280 Comm: kworker/0:3 Not tainted 4.15.0-rc9+ #20
> > [ 7384.326675] Hardware name: NotebookÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ N24_25BU/N24_25BU, BIOS 5.12 07/07/2017
> > [ 7384.326690] Workqueue: events btusb_work [btusb]
> > [ 7384.326699] Call Trace:
> > [ 7384.326711]Â dump_stack+0xaf/0x125
> > [ 7384.326722]Â ? dma_virt_map_sg+0x14b/0x14b
> > [ 7384.326733]Â ? show_regs_print_info+0xa/0xa
> > [ 7384.326753]Â print_address_description+0x7a/0x440
> > [ 7384.326768]Â ? xhci_trb_virt_to_dma.part.24+0x1c/0x80
> > [ 7384.326778]Â kasan_report+0x1dc/0x450
> > [ 7384.326796]Â ? xhci_trb_virt_to_dma.part.24+0x1c/0x80
> > [ 7384.326811]Â xhci_trb_virt_to_dma.part.24+0x1c/0x80
> > [ 7384.326824]Â xhci_urb_dequeue+0x987/0xd70
> > [ 7384.326850]Â ? ret_from_fork+0x35/0x40
> > [ 7384.326864]Â ? xhci_get_endpoint_flag+0x80/0x80
> > [ 7384.326884]Â ? trace_graph_entry+0x178/0x380
> > [ 7384.326891]Â ? xhci_get_endpoint_flag+0x80/0x80
> > [ 7384.326905]Â ? xhci_get_endpoint_flag+0x80/0x80
> > [ 7384.326926]Â ? prepare_ftrace_return+0x1c5/0x2c0
> > [ 7384.326939]Â ? usb_hcd_flush_endpoint+0x185/0x440
> > [ 7384.326949]Â ? addr_from_call+0xe0/0xe0
> > [ 7384.326957]Â ? ftrace_lookup_ip+0x154/0x250
> > [ 7384.326965]Â ? xhci_get_endpoint_flag+0x80/0x80
> > [ 7384.326975]Â ? is_ftrace_trampoline+0x10/0x10
> > [ 7384.327007]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327018]Â ? usb_disable_endpoint+0x76/0x110
> > [ 7384.327025]Â ? rcu_sched_qs.part.49+0x70/0x70
> > [ 7384.327033]Â ? xhci_get_endpoint_flag+0x80/0x80
> > [ 7384.327038]Â ? unlink1+0x79/0x270
> > [ 7384.327052]Â usb_hcd_flush_endpoint+0x185/0x440
> > [ 7384.327064]Â ? usb_hcd_unlink_urb+0x210/0x210
> > [ 7384.327069]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327076]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327087]Â ? usb_disable_endpoint+0x64/0x110
> > [ 7384.327101]Â usb_disable_endpoint+0x76/0x110
> > [ 7384.327110]Â usb_disable_interface+0x98/0xf0
> > [ 7384.327124]Â usb_set_interface+0x29d/0x630
> > [ 7384.327143]Â btusb_work+0x400/0x881 [btusb]
> > [ 7384.327158]Â process_one_work+0x677/0xd70
> > [ 7384.327174]Â ? create_worker+0x360/0x360
> > [ 7384.327180]Â ? compat_start_thread+0x70/0x70
> > [ 7384.327185]Â ? __switch_to_asm+0x34/0x70
> > [ 7384.327196]Â ? finish_task_switch+0x12b/0x540
> > [ 7384.327201]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327206]Â ? __switch_to_asm+0x40/0x70
> > [ 7384.327211]Â ? __switch_to_asm+0x34/0x70
> > [ 7384.327220]Â ? trace_event_raw_event_sched_wake_idle_without_ipi+0x160/0x160
> > [ 7384.327226]Â ? __switch_to_asm+0x34/0x70
> > [ 7384.327234]Â ? ftrace_lookup_ip+0x154/0x250
> > [ 7384.327247]Â ? __schedule+0x4f3/0x12f0
> > [ 7384.327267]Â ? create_worker+0x360/0x360
> > [ 7384.327277]Â ? create_worker+0x360/0x360
> > [ 7384.327285]Â ? worker_thread+0x1f8/0xf70
> > [ 7384.327292]Â ? addr_from_call+0xe0/0xe0
> > [ 7384.327298]Â ? task_change_group_fair+0x5c0/0x5c0
> > [ 7384.327303]Â ? create_worker+0x360/0x360
> > [ 7384.327315]Â ? schedule+0xe5/0x2c0
> > [ 7384.327320]Â ? move_linked_works+0x2e9/0x460
> > [ 7384.327326]Â ? __schedule+0x12f0/0x12f0
> > [ 7384.327338]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327353]Â ? worker_thread+0x6c5/0xf70
> > [ 7384.327367]Â worker_thread+0x1f8/0xf70
> > [ 7384.327394]Â ? process_one_work+0xd70/0xd70
> > [ 7384.327401]Â ? trace_graph_entry+0x178/0x380
> > [ 7384.327406]Â ? trace_event_raw_event_sched_wake_idle_without_ipi+0x160/0x160
> > [ 7384.327416]Â ? prepare_ftrace_return+0x1c5/0x2c0
> > [ 7384.327424]Â ? __schedule+0x4cb/0x12f0
> > [ 7384.327430]Â ? addr_from_call+0xe0/0xe0
> > [ 7384.327437]Â ? trace_event_raw_event_sched_wake_idle_without_ipi+0x160/0x160
> > [ 7384.327444]Â ? __switch_to+0x443/0xad0
> > [ 7384.327457]Â ? compat_start_thread+0x70/0x70
> > [ 7384.327462]Â ? __switch_to_asm+0x34/0x70
> > [ 7384.327474]Â ? finish_task_switch+0x12b/0x540
> > [ 7384.327480]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327488]Â ? __switch_to_asm+0x40/0x70
> > [ 7384.327496]Â ? __switch_to_asm+0x34/0x70
> > [ 7384.327508]Â ? trace_event_raw_event_sched_wake_idle_without_ipi+0x160/0x160
> > [ 7384.327521]Â ? ftrace_lookup_ip+0x154/0x250
> > [ 7384.327535]Â ? __schedule+0x4f3/0x12f0
> > [ 7384.327555]Â ? process_one_work+0xd70/0xd70
> > [ 7384.327565]Â ? process_one_work+0xd70/0xd70
> > [ 7384.327573]Â ? kthread+0x205/0x2d0
> > [ 7384.327579]Â ? addr_from_call+0xe0/0xe0
> > [ 7384.327586]Â ? process_one_work+0xd70/0xd70
> > [ 7384.327597]Â ? schedule+0xe5/0x2c0
> > [ 7384.327605]Â ? __schedule+0x12f0/0x12f0
> > [ 7384.327615]Â ? process_one_work+0xd70/0xd70
> > [ 7384.327621]Â ? ftrace_graph_caller+0x62/0xa0
> > [ 7384.327628]Â ? kasan_kmalloc+0xa0/0xd0
> > [ 7384.327640]Â ? __kthread_parkme+0xac/0x110
> > [ 7384.327652]Â ? process_one_work+0xd70/0xd70
> > [ 7384.327658]Â kthread+0x205/0x2d0
> > [ 7384.327665]Â ? kthread_create_worker_on_cpu+0xc0/0xc0
> > [ 7384.327675]Â ret_from_fork+0x35/0x40
> >
> > [ 7384.327702] Allocated by task 13479:
> > [ 7384.327709]Â kasan_kmalloc+0xa0/0xd0
> > [ 7384.327714]Â kmem_cache_alloc_trace+0x139/0x360
> > [ 7384.327719]Â xhci_segment_alloc+0x9e/0x270
> > [ 7384.327724]Â xhci_alloc_segments_for_ring+0x37/0x160
> > [ 7384.327729]Â xhci_ring_alloc.constprop.19+0x176/0x410
> > [ 7384.327733]Â xhci_endpoint_init+0x313/0x8f0
> > [ 7384.327738]Â xhci_add_endpoint+0x214/0x5c0
> > [ 7384.327743]Â usb_hcd_alloc_bandwidth+0x5fa/0x800
> > [ 7384.327748]Â usb_set_interface+0x174/0x630
> > [ 7384.327756]Â btusb_work+0x210/0x881 [btusb]
> > [ 7384.327761]Â process_one_work+0x677/0xd70
> > [ 7384.327765]Â worker_thread+0x1f8/0xf70
> > [ 7384.327769]Â kthread+0x205/0x2d0
> > [ 7384.327774]Â ret_from_fork+0x35/0x40
> >
> > [ 7384.327782] Freed by task 17280:
> > [ 7384.327788]Â kasan_slab_free+0x71/0xc0
> > [ 7384.327793]Â kfree+0xd2/0x390
> > [ 7384.327798]Â xhci_ring_free.part.15+0xe5/0x2b0
> > [ 7384.327803]Â xhci_free_endpoint_ring+0x4b/0xb0
> > [ 7384.327808]Â xhci_check_bandwidth+0x2e7/0x590
> > [ 7384.327813]Â usb_hcd_alloc_bandwidth+0x43d/0x800
> > [ 7384.327818]Â usb_set_interface+0x174/0x630
> > [ 7384.327825]Â btusb_work+0x400/0x881 [btusb]
> > [ 7384.327830]Â process_one_work+0x677/0xd70
> > [ 7384.327834]Â worker_thread+0x1f8/0xf70
> > [ 7384.327838]Â kthread+0x205/0x2d0
> > [ 7384.327843]Â ret_from_fork+0x35/0x40
> >
> > [ 7384.327851] The buggy address belongs to the object at ffff88068c491c00
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ which belongs to the cache kmalloc-64 of size 64
> > [ 7384.327859] The buggy address is located 0 bytes inside of
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 64-byte region [ffff88068c491c00, ffff88068c491c40)
> > [ 7384.327865] The buggy address belongs to the page:
> > [ 7384.327872] page:ffffea001a312440 count:1 mapcount:0 mapping:ÂÂÂÂÂÂÂÂÂ (null) index:0xffff88068c491300
> > [ 7384.327881] flags: 0x17fff8000000100(slab)
> > [ 7384.327889] raw: 017fff8000000100 0000000000000000 ffff88068c491300 00000001002a0028
> > [ 7384.327896] raw: ffffea001ab82460 ffffea001aed5ee0 ffff88080c8036c0 0000000000000000
> > [ 7384.327901] page dumped because: kasan: bad access detected
> >
> > [ 7384.327909] Memory state around the buggy address:
> > [ 7384.327928]Â ffff88068c491b00: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
> > [ 7384.327933]Â ffff88068c491b80: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
> > [ 7384.327938] >ffff88068c491c00: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
> > [ 7384.327943]ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^
> > [ 7384.327948]Â ffff88068c491c80: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
> > [ 7384.327953]Â ffff88068c491d00: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
> > [ 7384.327958] ==================================================================
>
>
> Kind regards,
>
> Paul