[alsa-devel] KASAN: slab-out-of-bounds Read in build_audio_procunit (2)

Andrey Konovalov andreyknvl at google.com
Tue Dec 3 15:04:25 CET 2019 

On Thu, Nov 7, 2019 at 4:34 PM syzbot
<syzbot+622d4ecb979f45c6a775 at syzkaller.appspotmail.com> wrote:
>
> 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 at 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
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller at googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

#syz fix: ALSA: usb-audio: Fix incorrect size check for
processing/extension units

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