Hi!

I've got the following report while fuzzing the kernel with syzkaller.

On commit e1d1ea549b57790a3d8cf6300e6ef86118d692a3 (4.15-rc1).

================================================================== BUG: KASAN: slab-out-of-bounds in parse_audio_unit+0x2e08/0x31d0 Read of size 1 at addr ffff88006998ff20 by task kworker/1:1/1495

CPU: 1 PID: 1495 Comm: kworker/1:1 Not tainted 4.14.0-57501-g9284d204d604 #119 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: usb_hub_wq hub_event Call Trace: __dump_stack lib/dump_stack.c:17 dump_stack+0xe1/0x157 lib/dump_stack.c:53 print_address_description+0x71/0x234 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 kasan_report+0x173/0x270 mm/kasan/report.c:409 __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:427 parse_audio_feature_unit sound/usb/mixer.c:1472 parse_audio_unit+0x2e08/0x31d0 sound/usb/mixer.c:2213 snd_usb_mixer_controls+0x2ec/0x750 sound/usb/mixer.c:2320 snd_usb_create_mixer+0x209/0xbe0 sound/usb/mixer.c:2566 create_standard_mixer_quirk+0x61/0x80 sound/usb/quirks.c:516 snd_usb_create_quirk+0xa6/0x120 sound/usb/quirks.c:560 create_composite_quirk+0x1e0/0x420 sound/usb/quirks.c:59 snd_usb_create_quirk+0xa6/0x120 sound/usb/quirks.c:560 usb_audio_probe+0x1220/0x1f70 sound/usb/card.c:618 usb_probe_interface+0x324/0x940 drivers/usb/core/driver.c:361 really_probe drivers/base/dd.c:424 driver_probe_device+0x564/0x820 drivers/base/dd.c:566 __device_attach_driver+0x25d/0x2d0 drivers/base/dd.c:662 bus_for_each_drv+0xff/0x160 drivers/base/bus.c:463 __device_attach+0x1ab/0x2a0 drivers/base/dd.c:719 device_initial_probe+0x1f/0x30 drivers/base/dd.c:766 bus_probe_device+0x1fc/0x2a0 drivers/base/bus.c:523 device_add+0xc27/0x15a0 drivers/base/core.c:1835 usb_set_configuration+0xd55/0x17a0 drivers/usb/core/message.c:1967 generic_probe+0xbb/0x120 drivers/usb/core/generic.c:174 usb_probe_device+0xab/0x100 drivers/usb/core/driver.c:266 really_probe drivers/base/dd.c:424 driver_probe_device+0x564/0x820 drivers/base/dd.c:566 __device_attach_driver+0x25d/0x2d0 drivers/base/dd.c:662 bus_for_each_drv+0xff/0x160 drivers/base/bus.c:463 __device_attach+0x1ab/0x2a0 drivers/base/dd.c:719 device_initial_probe+0x1f/0x30 drivers/base/dd.c:766 bus_probe_device+0x1fc/0x2a0 drivers/base/bus.c:523 device_add+0xc27/0x15a0 drivers/base/core.c:1835 usb_new_device+0x7fa/0x1090 drivers/usb/core/hub.c:2538 hub_port_connect drivers/usb/core/hub.c:5000 hub_port_connect_change drivers/usb/core/hub.c:5106 port_event drivers/usb/core/hub.c:5212 hub_event_impl+0x17bc/0x3440 drivers/usb/core/hub.c:5324 hub_event+0x38/0x50 drivers/usb/core/hub.c:5222 process_one_work+0x944/0x15f0 kernel/workqueue.c:2112 worker_thread+0xef/0x10d0 kernel/workqueue.c:2246 kthread+0x367/0x420 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437

Allocated by task 1495: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:551 __kmalloc+0x1bc/0x300 mm/slub.c:3762 kmalloc ./include/linux/slab.h:504 usb_get_configuration+0x299/0x4e60 drivers/usb/core/config.c:856 usb_enumerate_device drivers/usb/core/hub.c:2371 usb_new_device+0xab1/0x1090 drivers/usb/core/hub.c:2507 hub_port_connect drivers/usb/core/hub.c:5000 hub_port_connect_change drivers/usb/core/hub.c:5106 port_event drivers/usb/core/hub.c:5212 hub_event_impl+0x17bc/0x3440 drivers/usb/core/hub.c:5324 hub_event+0x38/0x50 drivers/usb/core/hub.c:5222 process_one_work+0x944/0x15f0 kernel/workqueue.c:2112 worker_thread+0xef/0x10d0 kernel/workqueue.c:2246 kthread+0x367/0x420 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437

Freed by task 5251: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 slab_free_hook mm/slub.c:1391 slab_free_freelist_hook mm/slub.c:1412 slab_free mm/slub.c:2968 kfree+0xf2/0x2e0 mm/slub.c:3899 kzfree+0x2d/0x40 mm/slab_common.c:1482 aa_free_task_context+0x13a/0x170 security/apparmor/context.c:54 apparmor_cred_free+0x38/0x70 security/apparmor/lsm.c:58 security_cred_free+0x4d/0x90 security/security.c:995 put_cred_rcu+0x72/0x2a0 kernel/cred.c:117 __rcu_reclaim kernel/rcu/rcu.h:195 rcu_do_batch kernel/rcu/tree.c:2758 invoke_rcu_callbacks kernel/rcu/tree.c:3012 __rcu_process_callbacks kernel/rcu/tree.c:2979 rcu_process_callbacks+0x4df/0xcf0 kernel/rcu/tree.c:2996 __do_softirq+0x2e0/0x88e kernel/softirq.c:285

The buggy address belongs to the object at ffff88006998ff00 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes to the right of 32-byte region [ffff88006998ff00, ffff88006998ff20) The buggy address belongs to the page: page:ffffea0001a663c0 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x100000000000100(slab) raw: 0100000000000100 0000000000000000 0000000000000000 0000000180550055 raw: ffffea0001aea900 0000000200000002 ffff88006c803980 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff88006998fe00: fc fc fb fb fb fb fc fc 00 00 00 fc fc fc fb fb ffff88006998fe80: fb fb fc fc fb fb fb fb fc fc fb fb fb fb fc fc

ffff88006998ff00: 00 00 00 00 fc fc fb fb fb fb fc fc fb fb fb fb

^ ffff88006998ff80: fc fc 00 00 00 00 fc fc fb fb fb fb fc fc fc fc ffff880069990000: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ==================================================================