Re: KASAN: use-after-free Write in usbvision_scratch_alloc

[Andrey Konovalov]

On Mon, Jul 29, 2019 at 1:48 PM syzbot
<syzbot+fa317310495b601f2c3e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=14089192600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> dashboard link: https://syzkaller.appspot.com/bug?extid=fa317310495b601f2c3e
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+fa317310495b601f2c3e@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: use-after-free in usbvision_scratch_alloc+0x8c/0xa0
> drivers/media/usb/usbvision/usbvision-core.c:350
> Write of size 8 at addr ffff8881cd2adc00 by task v4l_id/5718
>
> CPU: 0 PID: 5718 Comm: v4l_id Not tainted 5.2.0-rc6+ #15
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0xca/0x13e lib/dump_stack.c:113
>   print_address_description+0x67/0x231 mm/kasan/report.c:188
>   __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
>   kasan_report+0xe/0x20 mm/kasan/common.c:614
>   usbvision_scratch_alloc+0x8c/0xa0
> drivers/media/usb/usbvision/usbvision-core.c:350
>   usbvision_v4l2_open+0x148/0x2f0
> drivers/media/usb/usbvision/usbvision-video.c:325
>   v4l2_open+0x1af/0x350 drivers/media/v4l2-core/v4l2-dev.c:423
>   chrdev_open+0x219/0x5c0 fs/char_dev.c:413
>   do_dentry_open+0x497/0x1040 fs/open.c:778
>   do_last fs/namei.c:3416 [inline]
>   path_openat+0x1430/0x3ff0 fs/namei.c:3533
>   do_filp_open+0x1a1/0x280 fs/namei.c:3563
>   do_sys_open+0x3c0/0x580 fs/open.c:1070
>   do_syscall_64+0xb7/0x560 arch/x86/entry/common.c:301
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x7f655947e120
> Code: 48 8b 15 1b 4d 2b 00 f7 d8 64 89 02 83 c8 ff c3 90 90 90 90 90 90 90
> 90 90 90 83 3d d5 a4 2b 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff
> ff 73 31 c3 48 83 ec 08 e8 5e 8c 01 00 48 89 04 24
> RSP: 002b:00007ffd1bdddb58 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> RAX: ffffffffffffffda RBX: 00007ffd1bdddcb8 RCX: 00007f655947e120
> RDX: 00007f6559733138 RSI: 0000000000000000 RDI: 00007ffd1bdddf1c
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884
> R13: 00007ffd1bdddcb0 R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 2779:
>   save_stack+0x1b/0x80 mm/kasan/common.c:71
>   set_track mm/kasan/common.c:79 [inline]
>   __kasan_kmalloc mm/kasan/common.c:489 [inline]
>   __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:462
>   kmalloc include/linux/slab.h:547 [inline]
>   kzalloc include/linux/slab.h:742 [inline]
>   usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1310 [inline]
>   usbvision_probe.cold+0x586/0x1d69
> drivers/media/usb/usbvision/usbvision-video.c:1464
>   usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
>   really_probe+0x281/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
>   bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x16f0 drivers/base/core.c:2111
>   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+0x281/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
>   bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x16f0 drivers/base/core.c:2111
>   usb_new_device.cold+0x6a4/0xe61 drivers/usb/core/hub.c:2536
>   hub_port_connect drivers/usb/core/hub.c:5098 [inline]
>   hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
>   port_event drivers/usb/core/hub.c:5359 [inline]
>   hub_event+0x1abd/0x3550 drivers/usb/core/hub.c:5441
>   process_one_work+0x905/0x1570 kernel/workqueue.c:2269
>   process_scheduled_works kernel/workqueue.c:2331 [inline]
>   worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
>   kthread+0x30b/0x410 kernel/kthread.c:255
>   ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>
> Freed by task 2779:
>   save_stack+0x1b/0x80 mm/kasan/common.c:71
>   set_track mm/kasan/common.c:79 [inline]
>   __kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
>   slab_free_hook mm/slub.c:1421 [inline]
>   slab_free_freelist_hook mm/slub.c:1448 [inline]
>   slab_free mm/slub.c:2994 [inline]
>   kfree+0xd7/0x280 mm/slub.c:3949
>   usbvision_release+0x181/0x1c0
> drivers/media/usb/usbvision/usbvision-video.c:1359
>   usbvision_disconnect+0x16c/0x1d0
> drivers/media/usb/usbvision/usbvision-video.c:1582
>   usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
>   __device_release_driver drivers/base/dd.c:1081 [inline]
>   device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1112
>   bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
>   device_del+0x460/0xb80 drivers/base/core.c:2274
>   usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
>   usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
>   hub_port_connect drivers/usb/core/hub.c:4949 [inline]
>   hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
>   port_event drivers/usb/core/hub.c:5359 [inline]
>   hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
>   process_one_work+0x905/0x1570 kernel/workqueue.c:2269
>   process_scheduled_works kernel/workqueue.c:2331 [inline]
>   worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
>   kthread+0x30b/0x410 kernel/kthread.c:255
>   ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>
> The buggy address belongs to the object at ffff8881cd2ac200
>   which belongs to the cache kmalloc-8k of size 8192
> The buggy address is located 6656 bytes inside of
>   8192-byte region [ffff8881cd2ac200, ffff8881cd2ae200)
> The buggy address belongs to the page:
> page:ffffea000734aa00 refcount:1 mapcount:0 mapping:ffff8881dac02400
> index:0x0 compound_mapcount: 0
> flags: 0x200000000010200(slab|head)
> raw: 0200000000010200 dead000000000100 dead000000000200 ffff8881dac02400
> raw: 0000000000000000 0000000080030003 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff8881cd2adb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff8881cd2adb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff8881cd2adc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                     ^
>   ffff8881cd2adc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff8881cd2add00: 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@xxxxxxxxxxxxxxxxx
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

Most probably the same bug as:

https://syzkaller.appspot.com/bug?extid=7fa38a608b1075dfd634

#syz dup: general protection fault in usb_set_interface