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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: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.