Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 19/28] ALSA: line6: Fix leftover URB at error-path during probe | Date | Mon, 16 Oct 2017 18:12:12 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai <tiwai@suse.de>
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@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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);
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