KASAN: slab-out-of-bounds Read in build_audio_procunit (2)

[syzbot <syzbot+622d4ecb979f45c6a775@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    d60bbfea usb: raw: add raw-gadget interface
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=132e5bcce00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=79de80330003b5f7
dashboard link: https://syzkaller.appspot.com/bug?extid=622d4ecb979f45c6a775
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1478c6b4e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=117cbf8ae00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+622d4ecb979f45c6a775@syzkaller.appspotmail.com

usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1: Product: syz
usb 1-1: Manufacturer: syz
usb 1-1: SerialNumber: syz
usb 1-1: 0:2 : does not exist
==================================================================
BUG: KASAN: slab-out-of-bounds in uac_extension_unit_iExtension  
include/uapi/linux/usb/audio.h:483 [inline]
BUG: KASAN: slab-out-of-bounds in build_audio_procunit+0xeab/0x13f0  
sound/usb/mixer.c:2434
Read of size 1 at addr ffff8881d4aaa735 by task kworker/1:2/83

CPU: 1 PID: 83 Comm: kworker/1:2 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0xca/0x13e lib/dump_stack.c:113
  print_address_description.constprop.0+0x36/0x50 mm/kasan/report.c:374
  __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:506
  kasan_report+0xe/0x20 mm/kasan/common.c:634
  uac_extension_unit_iExtension include/uapi/linux/usb/audio.h:483 [inline]
  build_audio_procunit+0xeab/0x13f0 sound/usb/mixer.c:2434
  parse_audio_extension_unit sound/usb/mixer.c:2483 [inline]
  parse_audio_unit+0x1812/0x36f0 sound/usb/mixer.c:2761
  snd_usb_mixer_controls+0x715/0xb90 sound/usb/mixer.c:3095
  snd_usb_create_mixer+0x2b5/0x1890 sound/usb/mixer.c:3445
  usb_audio_probe+0xc76/0x2010 sound/usb/card.c:653
  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x104/0x210 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
  device_add+0xae6/0x16f0 drivers/base/core.c:2202
  usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x104/0x210 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
  device_add+0xae6/0x16f0 drivers/base/core.c:2202
  usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2537
  hub_port_connect drivers/usb/core/hub.c:5184 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
  port_event drivers/usb/core/hub.c:5470 [inline]
  hub_event+0x1df8/0x3800 drivers/usb/core/hub.c:5552
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 83:
  save_stack+0x1b/0x80 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  __kasan_kmalloc mm/kasan/common.c:510 [inline]
  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:483
  kmalloc include/linux/slab.h:561 [inline]
  usb_get_configuration+0x311/0x3100 drivers/usb/core/config.c:862
  usb_enumerate_device drivers/usb/core/hub.c:2370 [inline]
  usb_new_device+0xd3/0x160 drivers/usb/core/hub.c:2506
  hub_port_connect drivers/usb/core/hub.c:5184 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
  port_event drivers/usb/core/hub.c:5470 [inline]
  hub_event+0x1df8/0x3800 drivers/usb/core/hub.c:5552
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 211:
  save_stack+0x1b/0x80 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  kasan_set_free_info mm/kasan/common.c:332 [inline]
  __kasan_slab_free+0x130/0x180 mm/kasan/common.c:471
  slab_free_hook mm/slub.c:1424 [inline]
  slab_free_freelist_hook mm/slub.c:1475 [inline]
  slab_free mm/slub.c:3025 [inline]
  kfree+0xe4/0x320 mm/slub.c:3977
  do_new_mount fs/namespace.c:2827 [inline]
  do_mount+0x68a/0x1bf0 fs/namespace.c:3143
  ksys_mount+0xd7/0x150 fs/namespace.c:3352
  __do_sys_mount fs/namespace.c:3366 [inline]
  __se_sys_mount fs/namespace.c:3363 [inline]
  __x64_sys_mount+0xba/0x150 fs/namespace.c:3363
  do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881d4aaa600
  which belongs to the cache kmalloc-256 of size 256
The buggy address is located 53 bytes to the right of
  256-byte region [ffff8881d4aaa600, ffff8881d4aaa700)
The buggy address belongs to the page:
page:ffffea000752aa80 refcount:1 mapcount:0 mapping:ffff8881da002780  
index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 ffffea000752c900 0000000a0000000a ffff8881da002780
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881d4aaa600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff8881d4aaa680: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
> ffff8881d4aaa700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                      ^
  ffff8881d4aaa780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8881d4aaa800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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