This is a note to let you know that I've just added the patch titled usb: hub: do not clear BOS field during reset device to the 4.3-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-hub-do-not-clear-bos-field-during-reset-device.patch and it can be found in the queue-4.3 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d8f00cd685f5c8e0def8593e520a7fef12c22407 Mon Sep 17 00:00:00 2001 From: "Du, Changbin" <changbin.du@xxxxxxxxx> Date: Mon, 18 Jan 2016 21:02:42 +0800 Subject: usb: hub: do not clear BOS field during reset device From: Du, Changbin <changbin.du@xxxxxxxxx> commit d8f00cd685f5c8e0def8593e520a7fef12c22407 upstream. In function usb_reset_and_verify_device, the old BOS descriptor may still be used before allocating a new one. (usb_unlocked_disable_lpm function uses it under the situation that it fails to disable lpm.) So we cannot set the udev->bos to NULL before that, just keep what it was. It will be overwrite when allocating a new one. Crash log: BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 IP: [<ffffffff8171f98d>] usb_enable_link_state+0x2d/0x2f0 Call Trace: [<ffffffff8171ed5b>] ? usb_set_lpm_timeout+0x12b/0x140 [<ffffffff8171fcd1>] usb_enable_lpm+0x81/0xa0 [<ffffffff8171fdd8>] usb_disable_lpm+0xa8/0xc0 [<ffffffff8171fe1c>] usb_unlocked_disable_lpm+0x2c/0x50 [<ffffffff81723933>] usb_reset_and_verify_device+0xc3/0x710 [<ffffffff8172c4ed>] ? usb_sg_wait+0x13d/0x190 [<ffffffff81724743>] usb_reset_device+0x133/0x280 [<ffffffff8179ccd1>] usb_stor_port_reset+0x61/0x70 [<ffffffff8179cd68>] usb_stor_invoke_transport+0x88/0x520 Signed-off-by: Du, Changbin <changbin.du@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/core/hub.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -5377,7 +5377,6 @@ static int usb_reset_and_verify_device(s } bos = udev->bos; - udev->bos = NULL; for (i = 0; i < SET_CONFIG_TRIES; ++i) { @@ -5470,8 +5469,11 @@ done: usb_set_usb2_hardware_lpm(udev, 1); usb_unlocked_enable_lpm(udev); usb_enable_ltm(udev); - usb_release_bos_descriptor(udev); - udev->bos = bos; + /* release the new BOS descriptor allocated by hub_port_init() */ + if (udev->bos != bos) { + usb_release_bos_descriptor(udev); + udev->bos = bos; + } return 0; re_enumerate: Patches currently in stable-queue which might be from changbin.du@xxxxxxxxx are queue-4.3/usb-hub-do-not-clear-bos-field-during-reset-device.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html