• Guenter Roeck's avatar
    usb: hub: Do not attempt to autosuspend disconnected devices · f5cccf49
    Guenter Roeck authored
    While running a bind/unbind stress test with the dwc3 usb driver on rk3399,
    the following crash was observed.
    
    Unable to handle kernel NULL pointer dereference at virtual address 00000218
    pgd = ffffffc00165f000
    [00000218] *pgd=000000000174f003, *pud=000000000174f003,
    				*pmd=0000000001750003, *pte=00e8000001751713
    Internal error: Oops: 96000005 [#1] PREEMPT SMP
    Modules linked in: uinput uvcvideo videobuf2_vmalloc cmac
    ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat rfcomm
    xt_mark fuse bridge stp llc zram btusb btrtl btbcm btintel bluetooth
    ip6table_filter mwifiex_pcie mwifiex cfg80211 cdc_ether usbnet r8152 mii joydev
    snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device ppp_async
    ppp_generic slhc tun
    CPU: 1 PID: 29814 Comm: kworker/1:1 Not tainted 4.4.52 #507
    Hardware name: Google Kevin (DT)
    Workqueue: pm pm_runtime_work
    task: ffffffc0ac540000 ti: ffffffc0af4d4000 task.ti: ffffffc0af4d4000
    PC is at autosuspend_check+0x74/0x174
    LR is at autosuspend_check+0x70/0x174
    ...
    Call trace:
    [<ffffffc00080dcc0>] autosuspend_check+0x74/0x174
    [<ffffffc000810500>] usb_runtime_idle+0x20/0x40
    [<ffffffc000785ae0>] __rpm_callback+0x48/0x7c
    [<ffffffc000786af0>] rpm_idle+0x1e8/0x498
    [<ffffffc000787cdc>] pm_runtime_work+0x88/0xcc
    [<ffffffc000249bb8>] process_one_work+0x390/0x6b8
    [<ffffffc00024abcc>] worker_thread+0x480/0x610
    [<ffffffc000251a80>] kthread+0x164/0x178
    [<ffffffc0002045d0>] ret_from_fork+0x10/0x40
    
    Source:
    
    (gdb) l *0xffffffc00080dcc0
    0xffffffc00080dcc0 is in autosuspend_check
    (drivers/usb/core/driver.c:1778).
    1773		/* We don't need to check interfaces that are
    1774		 * disabled for runtime PM.  Either they are unbound
    1775		 * or else their drivers don't support autosuspend
    1776		 * and so they are permanently active.
    1777		 */
    1778		if (intf->dev.power.disable_depth)
    1779			continue;
    1780		if (atomic_read(&intf->dev.power.usage_count) > 0)
    1781			return -EBUSY;
    1782		w |= intf->needs_remote_wakeup;
    
    Code analysis shows that intf is set to NULL in usb_disable_device() prior
    to setting actconfig to NULL. At the same time, usb_runtime_idle() does not
    lock the usb device, and neither does any of the functions in the
    traceback. This means that there is no protection against a race condition
    where usb_disable_device() is removing dev->actconfig->interface[] pointers
    while those are being accessed from autosuspend_check().
    
    To solve the problem, synchronize and validate device state between
    autosuspend_check() and usb_disconnect().
    Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    f5cccf49
driver.c 55.1 KB