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 my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 80e457699a8dbdd70f2d26911e46f538645c55fc Mon Sep 17 00:00:00 2001

From: Yu Chen chenyu56@huawei.com Date: Fri, 1 Dec 2017 13:41:20 +0200 Subject: usb: xhci: fix panic in xhci_free_virt_devices_depth_first

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@google.com Cc: stable@vger.kernel.org # v4.10+ Reviewed-by: Guenter Roeck groeck@chromium.org Tested-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Fan Ning fanning4@hisilicon.com Signed-off-by: Li Rui lirui39@hisilicon.com Signed-off-by: yangdi yangdi10@hisilicon.com Signed-off-by: Yu Chen chenyu56@huawei.com Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/host/xhci-mem.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index e1fba4688509..15f7d422885f 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -934,6 +934,12 @@ void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_id) 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 */ @@ -947,6 +953,7 @@ void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_id) } } } +out: /* we are now at a leaf device */ xhci_debugfs_remove_slot(xhci, slot_id); xhci_free_virt_device(xhci, slot_id);