This is a note to let you know that I've just added the patch titled ALSA: line6: Fix leftover URB at error-path during probe 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: alsa-line6-fix-leftover-urb-at-error-path-during-probe.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 c95072b3d88fac4be295815f2b67df366c0c297f Mon Sep 17 00:00:00 2001 From: Takashi Iwai <tiwai@xxxxxxx> Date: Mon, 9 Oct 2017 14:51:23 +0200 Subject: ALSA: line6: Fix leftover URB at error-path during probe From: Takashi Iwai <tiwai@xxxxxxx> commit c95072b3d88fac4be295815f2b67df366c0c297f upstream. While line6_probe() may kick off URB for a control MIDI endpoint, the function doesn't clean up it properly at its error path. This results in a leftover URB action that is eventually triggered later and causes an Oops like: general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 0 Comm: swapper/1 Not tainted RIP: 0010:usb_fill_bulk_urb ./include/linux/usb.h:1619 RIP: 0010:line6_start_listen+0x3fe/0x9e0 sound/usb/line6/driver.c:76 Call Trace: <IRQ> line6_data_received+0x1f7/0x470 sound/usb/line6/driver.c:326 __usb_hcd_giveback_urb+0x2e0/0x650 drivers/usb/core/hcd.c:1779 usb_hcd_giveback_urb+0x337/0x420 drivers/usb/core/hcd.c:1845 dummy_timer+0xba9/0x39f0 drivers/usb/gadget/udc/dummy_hcd.c:1965 call_timer_fn+0x2a2/0x940 kernel/time/timer.c:1281 .... Since the whole clean-up procedure is done in line6_disconnect() callback, we can simply call it in the error path instead of open-coding the whole again. It'll fix such an issue automagically. The bug was spotted by syzkaller. Fixes: eedd0e95d355 ("ALSA: line6: Don't forget to call driver's destructor at error path") Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- sound/usb/line6/driver.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/sound/usb/line6/driver.c +++ b/sound/usb/line6/driver.c @@ -586,9 +586,10 @@ int line6_probe(struct usb_interface *in return 0; error: - if (line6->disconnect) - line6->disconnect(line6); - snd_card_free(card); + /* we can call disconnect callback here because no close-sync is + * needed yet at this point + */ + line6_disconnect(interface); return ret; } EXPORT_SYMBOL_GPL(line6_probe); Patches currently in stable-queue which might be from tiwai@xxxxxxx are queue-4.4/alsa-caiaq-fix-stray-urb-at-probe-error-path.patch queue-4.4/alsa-seq-fix-copy_from_user-call-inside-lock.patch queue-4.4/alsa-seq-fix-use-after-free-at-creating-a-port.patch queue-4.4/alsa-line6-fix-leftover-urb-at-error-path-during-probe.patch queue-4.4/alsa-usb-audio-kill-stray-urb-at-exiting.patch