This is a note to let you know that I've just added the patch titled usb: xhci: fix panic in xhci_free_virt_devices_depth_first to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-xhci-fix-panic-in-xhci_free_virt_devices_depth_first.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 80e457699a8dbdd70f2d26911e46f538645c55fc Mon Sep 17 00:00:00 2001 From: Yu Chen <chenyu56@xxxxxxxxxx> Date: Fri, 1 Dec 2017 13:41:20 +0200 Subject: usb: xhci: fix panic in xhci_free_virt_devices_depth_first From: Yu Chen <chenyu56@xxxxxxxxxx> commit 80e457699a8dbdd70f2d26911e46f538645c55fc upstream. Check vdev->real_port 0 to avoid panic [ 9.261347] [<ffffff800884a390>] xhci_free_virt_devices_depth_first+0x58/0x108 [ 9.261352] [<ffffff800884a814>] xhci_mem_cleanup+0x1bc/0x570 [ 9.261355] [<ffffff8008842de8>] xhci_stop+0x140/0x1c8 [ 9.261365] [<ffffff80087ed304>] usb_remove_hcd+0xfc/0x1d0 [ 9.261369] [<ffffff80088551c4>] xhci_plat_remove+0x6c/0xa8 [ 9.261377] [<ffffff80086e928c>] platform_drv_remove+0x2c/0x70 [ 9.261384] [<ffffff80086e6ea0>] __device_release_driver+0x80/0x108 [ 9.261387] [<ffffff80086e7a1c>] device_release_driver+0x2c/0x40 [ 9.261392] [<ffffff80086e5f28>] bus_remove_device+0xe0/0x120 [ 9.261396] [<ffffff80086e2e34>] device_del+0x114/0x210 [ 9.261399] [<ffffff80086e9e00>] platform_device_del+0x30/0xa0 [ 9.261403] [<ffffff8008810bdc>] dwc3_otg_work+0x204/0x488 [ 9.261407] [<ffffff80088133fc>] event_work+0x304/0x5b8 [ 9.261414] [<ffffff80080e31b0>] process_one_work+0x148/0x490 [ 9.261417] [<ffffff80080e3548>] worker_thread+0x50/0x4a0 [ 9.261421] [<ffffff80080e9ea0>] kthread+0xe8/0x100 [ 9.261427] [<ffffff8008083680>] ret_from_fork+0x10/0x50 The problem can occur if xhci_plat_remove() is called shortly after xhci_plat_probe(). While xhci_free_virt_devices_depth_first been called before the device has been setup and get real_port initialized. The problem occurred on Hikey960 and was reproduced by Guenter Roeck on Kevin with chromeos-4.4. Fixes: ee8665e28e8d ("xhci: free xhci virtual devices with leaf nodes first") Cc: Guenter Roeck <groeck@xxxxxxxxxx> Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx> Signed-off-by: Fan Ning <fanning4@xxxxxxxxxxxxx> Signed-off-by: Li Rui <lirui39@xxxxxxxxxxxxx> Signed-off-by: yangdi <yangdi10@xxxxxxxxxxxxx> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/host/xhci-mem.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -981,6 +981,12 @@ void xhci_free_virt_devices_depth_first( if (!vdev) return; + if (vdev->real_port == 0 || + vdev->real_port > HCS_MAX_PORTS(xhci->hcs_params1)) { + xhci_dbg(xhci, "Bad vdev->real_port.\n"); + goto out; + } + tt_list_head = &(xhci->rh_bw[vdev->real_port - 1].tts); list_for_each_entry_safe(tt_info, next, tt_list_head, tt_list) { /* is this a hub device that added a tt_info to the tts list */ @@ -994,6 +1000,7 @@ void xhci_free_virt_devices_depth_first( } } } +out: /* we are now at a leaf device */ xhci_free_virt_device(xhci, slot_id); } Patches currently in stable-queue which might be from chenyu56@xxxxxxxxxx are queue-4.4/usb-xhci-fix-panic-in-xhci_free_virt_devices_depth_first.patch queue-4.4/usb-dwc2-error-out-of-dwc2_hsotg_ep_disable-if-we-re-in-host-mode.patch queue-4.4/usb-dwc2-fix-udc-state-tracking.patch