Re: KASAN: use-after-free Write in v4l2_device_release

[Andrey Konovalov]

On Mon, Apr 29, 2019 at 2:06 PM syzbot
<syzbot+62d0ec9a8d05fffcf12e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    43151d6c usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan/tree/usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=13f56538a00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=4183eeef650d1234
> dashboard link: https://syzkaller.appspot.com/bug?extid=62d0ec9a8d05fffcf12e
> 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+62d0ec9a8d05fffcf12e@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: use-after-free in v4l2_device_release+0x3ce/0x408
> drivers/media/v4l2-core/v4l2-dev.c:197
> Write of size 8 at addr ffff88809a266c08 by task v4l_id/7544
>
> CPU: 1 PID: 7544 Comm: v4l_id Not tainted 5.1.0-rc3-319004-g43151d6 #6
> 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+0xe8/0x16e lib/dump_stack.c:113
>   print_address_description+0x6c/0x236 mm/kasan/report.c:187
>   kasan_report.cold+0x1a/0x3c mm/kasan/report.c:317
>   v4l2_device_release+0x3ce/0x408 drivers/media/v4l2-core/v4l2-dev.c:197
>   device_release+0x7d/0x210 drivers/base/core.c:1064
>   kobject_cleanup lib/kobject.c:662 [inline]
>   kobject_release lib/kobject.c:691 [inline]
>   kref_put include/linux/kref.h:67 [inline]
>   kobject_put+0x1df/0x4f0 lib/kobject.c:708
>   put_device+0x21/0x30 drivers/base/core.c:2205
>   video_put drivers/media/v4l2-core/v4l2-dev.c:174 [inline]
>   v4l2_release+0x2d1/0x390 drivers/media/v4l2-core/v4l2-dev.c:469
>   __fput+0x2df/0x8c0 fs/file_table.c:278
>   task_work_run+0x149/0x1c0 kernel/task_work.c:113
>   tracehook_notify_resume include/linux/tracehook.h:188 [inline]
>   exit_to_usermode_loop+0x243/0x270 arch/x86/entry/common.c:166
>   prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
>   syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
>   do_syscall_64+0x40c/0x4f0 arch/x86/entry/common.c:293
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x7fc1f5f952b0
> Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0
> 07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff
> ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24
> RSP: 002b:00007ffd270a0138 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
> RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fc1f5f952b0
> RDX: 00007fc1f624bdf0 RSI: 0000000000000001 RDI: 0000000000000003
> RBP: 0000000000000000 R08: 00007fc1f624bdf0 R09: 000000000000000a
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884
> R13: 00007ffd270a0290 R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 5354:
>   set_track mm/kasan/common.c:87 [inline]
>   __kasan_kmalloc mm/kasan/common.c:497 [inline]
>   __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:470
>   slab_post_alloc_hook mm/slab.h:437 [inline]
>   slab_alloc_node mm/slub.c:2756 [inline]
>   __kmalloc_node_track_caller+0xf3/0x320 mm/slub.c:4372
>   alloc_dr drivers/base/devres.c:103 [inline]
>   devm_kmalloc+0x8c/0x190 drivers/base/devres.c:793
>   devm_kzalloc include/linux/device.h:679 [inline]
>   usb_raremono_probe+0x34/0x235 drivers/media/radio/radio-raremono.c:298
>   usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
>   really_probe+0x2da/0xb10 drivers/base/dd.c:509
>   driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
>   __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
>   bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x223/0x3a0 drivers/base/dd.c:844
>   bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
>   device_add+0xad2/0x16e0 drivers/base/core.c:2106
>   usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2023
>   generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
>   usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
>   really_probe+0x2da/0xb10 drivers/base/dd.c:509
>   driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
>   __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
>   bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x223/0x3a0 drivers/base/dd.c:844
>   bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
>   device_add+0xad2/0x16e0 drivers/base/core.c:2106
>   usb_new_device.cold+0x537/0xccf drivers/usb/core/hub.c:2534
>   hub_port_connect drivers/usb/core/hub.c:5089 [inline]
>   hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
>   port_event drivers/usb/core/hub.c:5350 [inline]
>   hub_event+0x138e/0x3b00 drivers/usb/core/hub.c:5432
>   process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
>   process_scheduled_works kernel/workqueue.c:2331 [inline]
>   worker_thread+0x7b0/0xe20 kernel/workqueue.c:2417
>   kthread+0x313/0x420 kernel/kthread.c:253
>   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
>
> Freed by task 5354:
>   set_track mm/kasan/common.c:87 [inline]
>   __kasan_slab_free+0x130/0x180 mm/kasan/common.c:459
>   slab_free_hook mm/slub.c:1429 [inline]
>   slab_free_freelist_hook+0x5e/0x140 mm/slub.c:1456
>   slab_free mm/slub.c:3003 [inline]
>   kfree+0xce/0x290 mm/slub.c:3958
>   release_nodes+0x4ac/0x920 drivers/base/devres.c:508
>   devres_release_all+0x79/0xc8 drivers/base/devres.c:529
>   __device_release_driver drivers/base/dd.c:1086 [inline]
>   device_release_driver_internal+0x23a/0x4f0 drivers/base/dd.c:1113
>   bus_remove_device+0x302/0x5c0 drivers/base/bus.c:556
>   device_del+0x467/0xb90 drivers/base/core.c:2269
>   usb_disable_device+0x242/0x790 drivers/usb/core/message.c:1237
>   usb_disconnect+0x298/0x870 drivers/usb/core/hub.c:2197
>   hub_port_connect drivers/usb/core/hub.c:4940 [inline]
>   hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
>   port_event drivers/usb/core/hub.c:5350 [inline]
>   hub_event+0xcd2/0x3b00 drivers/usb/core/hub.c:5432
>   process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
>   process_scheduled_works kernel/workqueue.c:2331 [inline]
>   worker_thread+0x7b0/0xe20 kernel/workqueue.c:2417
>   kthread+0x313/0x420 kernel/kthread.c:253
>   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
>
> The buggy address belongs to the object at ffff88809a266600
>   which belongs to the cache kmalloc-4k of size 4096
> The buggy address is located 1544 bytes inside of
>   4096-byte region [ffff88809a266600, ffff88809a267600)
> The buggy address belongs to the page:
> page:ffffea0002689800 count:1 mapcount:0 mapping:ffff88812c3f4600 index:0x0
> compound_mapcount: 0
> flags: 0xfff00000010200(slab|head)
> raw: 00fff00000010200 dead000000000100 dead000000000200 ffff88812c3f4600
> raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff88809a266b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff88809a266b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff88809a266c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                        ^
>   ffff88809a266c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff88809a266d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================

#syz dup: KASAN: use-after-free Read in v4l2_ioctl

>
>
> ---
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