This is a note to let you know that I've just added the patch titled usb: hub: Fix crash after failure to read BOS descriptor 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 7b2db29fbb4e766fcd02207eb2e2087170bd6ebc Mon Sep 17 00:00:00 2001 From: Guenter Roeck <linux@xxxxxxxxxxxx> Date: Wed, 8 Mar 2017 10:19:36 -0800 Subject: usb: hub: Fix crash after failure to read BOS descriptor If usb_get_bos_descriptor() returns an error, usb->bos will be NULL. Nevertheless, it is dereferenced unconditionally in hub_set_initial_usb2_lpm_policy() if usb2_hw_lpm_capable is set. This results in a crash. usb 5-1: unable to get BOS descriptor ... Unable to handle kernel NULL pointer dereference at virtual address 00000008 pgd = ffffffc00165f000 [00000008] *pgd=000000000174f003, *pud=000000000174f003, *pmd=0000000001750003, *pte=00e8000001751713 Internal error: Oops: 96000005 [#1] PREEMPT SMP Modules linked in: uinput uvcvideo videobuf2_vmalloc cmac [ ... ] CPU: 5 PID: 3353 Comm: kworker/5:3 Tainted: G B 4.4.52 #480 Hardware name: Google Kevin (DT) Workqueue: events driver_set_config_work task: ffffffc0c3690000 ti: ffffffc0ae9a8000 task.ti: ffffffc0ae9a8000 PC is at hub_port_init+0xc3c/0xd10 LR is at hub_port_init+0xc3c/0xd10 ... Call trace: [<ffffffc0007fbbfc>] hub_port_init+0xc3c/0xd10 [<ffffffc0007fbe2c>] usb_reset_and_verify_device+0x15c/0x82c [<ffffffc0007fc5e0>] usb_reset_device+0xe4/0x298 [<ffffffbffc0e3fcc>] rtl8152_probe+0x84/0x9b0 [r8152] [<ffffffc00080ca8c>] usb_probe_interface+0x244/0x2f8 [<ffffffc000774a24>] driver_probe_device+0x180/0x3b4 [<ffffffc000774e48>] __device_attach_driver+0xb4/0xe0 [<ffffffc000772168>] bus_for_each_drv+0xb4/0xe4 [<ffffffc0007747ec>] __device_attach+0xd0/0x158 [<ffffffc000775080>] device_initial_probe+0x24/0x30 [<ffffffc0007739d4>] bus_probe_device+0x50/0xe4 [<ffffffc000770bd0>] device_add+0x414/0x738 [<ffffffc000809fe8>] usb_set_configuration+0x89c/0x914 [<ffffffc00080a120>] driver_set_config_work+0xc0/0xf0 [<ffffffc000249bb8>] process_one_work+0x390/0x6b8 [<ffffffc00024abcc>] worker_thread+0x480/0x610 [<ffffffc000251a80>] kthread+0x164/0x178 [<ffffffc0002045d0>] ret_from_fork+0x10/0x40 Since we don't know anything about LPM capabilities without BOS descriptor, don't attempt to enable LPM if it is not available. Fixes: 890dae886721 ("xhci: Enable LPM support only for hardwired ...") Cc: stable <stable@xxxxxxxxxxxxxxx> Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> Acked-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/core/hub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index f0dd08198d74..5286bf67869a 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -4275,7 +4275,7 @@ static void hub_set_initial_usb2_lpm_policy(struct usb_device *udev) struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent); int connect_type = USB_PORT_CONNECT_TYPE_UNKNOWN; - if (!udev->usb2_hw_lpm_capable) + if (!udev->usb2_hw_lpm_capable || !udev->bos) return; if (hub) -- 2.12.0