On Thu, 24 Apr 2014, Sasha Levin wrote: > On 04/24/2014 03:24 PM, Greg KH wrote: > > On Thu, Apr 24, 2014 at 01:40:14PM -0400, Sasha Levin wrote: > >> > Hi all, > >> > > >> > While fuzzing with trinity inside a KVM tools guest running the latest -next > >> > kernel I've stumbled on the following: > >> > > >> > [ 1361.390880] WARNING: CPU: 10 PID: 24274 at lib/debugobjects.c:260 debug_print_object+0x8c/0xb0() > >> > [ 1361.391203] ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20 > >> > [ 1361.391203] Modules linked in: > >> > [ 1361.391203] CPU: 10 PID: 24274 Comm: trinity-c83 Not tainted 3.15.0-rc2-next-20140423-sasha-00018-gc4ff6c4 #408 > >> > [ 1361.391203] 0000000000000009 ffff8801de341c78 ffffffffb85271f2 0000000000000001 > >> > [ 1361.391203] ffff8801de341cc8 ffff8801de341cb8 ffffffffb515afcc ffff8801eb3ebd98 > >> > [ 1361.391203] ffff8801eb751870 ffffffffb9e76200 ffffffffb98dc502 ffffffffbc702550 > >> > [ 1361.391203] Call Trace: > >> > [ 1361.391203] dump_stack (lib/dump_stack.c:52) > >> > [ 1361.391203] warn_slowpath_common (kernel/panic.c:430) > >> > [ 1361.391203] warn_slowpath_fmt (kernel/panic.c:445) > >> > [ 1361.391203] debug_print_object (lib/debugobjects.c:262) > >> > [ 1361.391203] ? __queue_work (kernel/workqueue.c:1452) > >> > [ 1361.391203] __debug_check_no_obj_freed (lib/debugobjects.c:697) > >> > [ 1361.391203] debug_check_no_obj_freed (lib/debugobjects.c:726) > >> > [ 1361.391203] kmem_cache_free (mm/slub.c:2689 mm/slub.c:2717) > >> > [ 1361.391203] ? kmem_cache_destroy (mm/slab_common.c:363) > >> > [ 1361.391203] kmem_cache_destroy (mm/slab_common.c:363) > >> > [ 1361.391203] mon_text_release (drivers/usb/mon/mon_text.c:643) > >> > [ 1361.391203] __fput (fs/file_table.c:217) > >> > [ 1361.391203] ____fput (fs/file_table.c:253) > >> > [ 1361.391203] task_work_run (kernel/task_work.c:125 (discriminator 1)) > >> > [ 1361.391203] do_notify_resume (include/linux/tracehook.h:196 arch/x86/kernel/signal.c:751) > >> > [ 1361.391203] int_signal (arch/x86/kernel/entry_64.S:807) > > So you were running usbmon at the time? Were you actually monitoring a > > specific USB device/bus, or something else? > > This was inside a vm with no actual physical USB devices: > > # lsusb -t > lsusb: cannot open "/var/lib/usbutils/usb.ids", No such file or directory > /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ozwpan/8p, 12M > /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dummy_hcd/1p, 480M > |__ Port 1: Dev 2, If 0, Class=comm., Driver=cdc_eem, 480M > > Since it happened while I was fuzzing, I'm not sure what exactly was getting > monitored at that point. This is odd because the warning message indicates the something containing an active timer (a delayed_work structure?) was deallocated. But usbmon doesn't use either timers or work queues, and as far as I can see, neither does anything involved in kmem_cache management. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
