Hi Sasha,
i have (back)ported the patch to the older kernels mentioned below where the original patch failed.
The patch appended to this mail applies to v4.14.121, v4.9.178, v4.4.180 and v3.18.140. Some changes within the xhci driver prevented git from finding the correct position.
Hope this helps :-)
Best regards Carsten
Brrrr. IT stuff changed so i append the patch as text: ---
From b1ceb3787bcd6f3ae775eebead9a66b80a2b4314 Mon Sep 17 00:00:00 2001
From: Carsten Schmid carsten_schmid@mentor.com Date: Fri, 8 Mar 2019 15:15:52 +0100 Subject: [PATCH] usb: xhci: avoid null pointer deref when bos field is NULL
With defective USB sticks we see the following error happen: usb 1-3: new high-speed USB device number 6 using xhci_hcd usb 1-3: device descriptor read/64, error -71 usb 1-3: device descriptor read/64, error -71 usb 1-3: new high-speed USB device number 7 using xhci_hcd usb 1-3: device descriptor read/64, error -71 usb 1-3: unable to get BOS descriptor set usb 1-3: New USB device found, idVendor=0781, idProduct=5581 usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 ... BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
This comes from the following place: [ 1660.215380] IP: xhci_set_usb2_hardware_lpm+0xdf/0x3d0 [xhci_hcd] [ 1660.222092] PGD 0 P4D 0 [ 1660.224918] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 1660.425520] CPU: 1 PID: 38 Comm: kworker/1:1 Tainted: P U W O 4.14.67-apl #1 [ 1660.434277] Workqueue: usb_hub_wq hub_event [usbcore] [ 1660.439918] task: ffffa295b6ae4c80 task.stack: ffffad4580150000 [ 1660.446532] RIP: 0010:xhci_set_usb2_hardware_lpm+0xdf/0x3d0 [xhci_hcd] [ 1660.453821] RSP: 0018:ffffad4580153c70 EFLAGS: 00010046 [ 1660.459655] RAX: 0000000000000000 RBX: ffffa295b4d7c000 RCX: 0000000000000002 [ 1660.467625] RDX: 0000000000000002 RSI: ffffffff984a55b2 RDI: ffffffff984a55b2 [ 1660.475586] RBP: ffffad4580153cc8 R08: 0000000000d6520a R09: 0000000000000001 [ 1660.483556] R10: ffffad4580a004a0 R11: 0000000000000286 R12: ffffa295b4d7c000 [ 1660.491525] R13: 0000000000010648 R14: ffffa295a84e1800 R15: 0000000000000000 [ 1660.499494] FS: 0000000000000000(0000) GS:ffffa295bfc80000(0000) knlGS:0000000000000000 [ 1660.508530] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1660.514947] CR2: 0000000000000008 CR3: 000000025a114000 CR4: 00000000003406a0 [ 1660.522917] Call Trace: [ 1660.525657] usb_set_usb2_hardware_lpm+0x3d/0x70 [usbcore] [ 1660.531792] usb_disable_device+0x242/0x260 [usbcore] [ 1660.537439] usb_disconnect+0xc1/0x2b0 [usbcore] [ 1660.542600] hub_event+0x596/0x18f0 [usbcore] [ 1660.547467] ? trace_preempt_on+0xdf/0x100 [ 1660.552040] ? process_one_work+0x1c1/0x410 [ 1660.556708] process_one_work+0x1d2/0x410 [ 1660.561184] ? preempt_count_add.part.3+0x21/0x60 [ 1660.566436] worker_thread+0x2d/0x3f0 [ 1660.570522] kthread+0x122/0x140 [ 1660.574123] ? process_one_work+0x410/0x410 [ 1660.578792] ? kthread_create_on_node+0x60/0x60 [ 1660.583849] ret_from_fork+0x3a/0x50 [ 1660.587839] Code: 00 49 89 c3 49 8b 84 24 50 16 00 00 8d 4a ff 48 8d 04 c8 48 89 ca 4c 8b 10 45 8b 6a 04 48 8b 00 48 89 45 c0 49 8b 86 80 03 00 00 <48> 8b 40 08 8b 40 03 0f 1f 44 00 00 45 85 ff 0f 84 81 01 00 00 [ 1660.608980] RIP: xhci_set_usb2_hardware_lpm+0xdf/0x3d0 [xhci_hcd] RSP: ffffad4580153c70 [ 1660.617921] CR2: 0000000000000008
Tracking this down shows that udev->bos is NULL in the following code: (xhci.c, in xhci_set_usb2_hardware_lpm) field = le32_to_cpu(udev->bos->ext_cap->bmAttributes); <<<<<<< here
xhci_dbg(xhci, "%s port %d USB2 hardware LPM\n", enable ? "enable" : "disable", port_num + 1);
if (enable) { /* Host supports BESL timeout instead of HIRD */ if (udev->usb2_hw_lpm_besl_capable) { /* if device doesn't have a preferred BESL value use a * default one which works with mixed HIRD and BESL * systems. See XHCI_DEFAULT_BESL definition in xhci.h */ if ((field & USB_BESL_SUPPORT) && (field & USB_BESL_BASELINE_VALID)) hird = USB_GET_BESL_BASELINE(field); else hird = udev->l1_params.besl;
The failing case is when disabling LPM. So it is sufficient to avoid access to udev->bos by moving the instruction into the "enable" clause.
Signed-off-by: Carsten Schmid carsten_schmid@mentor.com --- drivers/usb/host/xhci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index c78de07c4d00..6001c3cefab3 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -4155,7 +4155,6 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd, pm_addr = port_array[port_num] + PORTPMSC; pm_val = readl(pm_addr); hlpm_addr = port_array[port_num] + PORTHLPMC; - field = le32_to_cpu(udev->bos->ext_cap->bmAttributes);
xhci_dbg(xhci, "%s port %d USB2 hardware LPM\n", enable ? "enable" : "disable", port_num + 1); @@ -4167,6 +4166,7 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd, * default one which works with mixed HIRD and BESL * systems. See XHCI_DEFAULT_BESL definition in xhci.h */ + field = le32_to_cpu(udev->bos->ext_cap->bmAttributes); if ((field & USB_BESL_SUPPORT) && (field & USB_BESL_BASELINE_VALID)) hird = USB_GET_BESL_BASELINE(field);