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BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023

CPU: 0 PID: 4758 Comm: syz-executor3 Not tainted 4.13.0-rc5+ #42
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_double_free+0x55/0x80 mm/kasan/report.c:333
 kasan_slab_free+0xa3/0xc0 mm/kasan/kasan.c:514
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xca/0x250 mm/slab.c:3820
 selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023
 security_tun_dev_free_security+0x48/0x80 security/security.c:1512
 tun_set_iff drivers/net/tun.c:1884 [inline]
 __tun_chr_ioctl+0x2ce6/0x3d50 drivers/net/tun.c:2064
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x4512e9
RSP: 002b:00007f93e9d1ec08 EFLAGS: 00000216 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 00000000004512e9
RDX: 0000000020511fd8 RSI: 00000000400454ca RDI: 0000000000000006
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004badb0
R13: 00000000ffffffff R14: 0000000020124ff3 R15: 0000000000000000

Allocated by task 4758:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x12f/0x740 mm/slab.c:3627
 kmalloc include/linux/slab.h:493 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 selinux_tun_dev_alloc_security+0x49/0x170 security/selinux/hooks.c:5012
 security_tun_dev_alloc_security+0x6d/0xa0 security/security.c:1506
 tun_set_iff drivers/net/tun.c:1839 [inline]
 __tun_chr_ioctl+0x1730/0x3d50 drivers/net/tun.c:2064
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 4758:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xca/0x250 mm/slab.c:3820
 selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023
 security_tun_dev_free_security+0x48/0x80 security/security.c:1512
 tun_free_netdev+0x13b/0x1b0 drivers/net/tun.c:1563
 register_netdevice+0x8d0/0xee0 net/core/dev.c:7605
 tun_set_iff drivers/net/tun.c:1859 [inline]
 __tun_chr_ioctl+0x1caf/0x3d50 drivers/net/tun.c:2064
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
 entry_SYSCALL_64_fastpath+0x1f/0xbe

The buggy address belongs to the object at ffff8801d02561c0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8801d02561c0, ffff8801d02561e0)
The buggy address belongs to the page:
page:ffffea0007409580 count:1 mapcount:0 mapping:ffff8801d0256000 index:0xffff8801d0256fc1
flags: 0x200000000000100(slab)
raw: 0200000000000100 ffff8801d0256000 ffff8801d0256fc1 0000000100000031
raw: ffffea000741e360 ffffea00074065e0 ffff8801dac001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d0256080: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d0256100: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801d0256180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                                           ^
 ffff8801d0256200: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d0256280: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
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