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BUG: KASAN: use-after-free in enqueue_timer include/linux/list.h:673 [inline]
BUG: KASAN: use-after-free in __mod_timer kernel/time/timer.c:1021 [inline]
BUG: KASAN: use-after-free in mod_timer+0x11d3/0x15b0 kernel/time/timer.c:1071
Write of size 8 at addr ffff88004f4e3cc8 by task syz-executor6/11791

CPU: 3 PID: 11791 Comm: syz-executor6 Not tainted 4.13.0-next-20170912+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 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_error mm/kasan/report.c:351 [inline]
 kasan_report+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:435
 enqueue_timer include/linux/list.h:673 [inline]
 __mod_timer kernel/time/timer.c:1021 [inline]
 mod_timer+0x11d3/0x15b0 kernel/time/timer.c:1071
 sk_reset_timer+0x22/0x50 net/core/sock.c:2664
 inet_csk_reset_xmit_timer include/net/inet_connection_sock.h:243 [inline]
 dccp_send_close+0x2ea/0x380 net/dccp/output.c:700
 dccp_terminate_connection net/dccp/proto.c:974 [inline]
 dccp_close+0x8b6/0xc10 net/dccp/proto.c:1037
 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425
 sock_release+0x8d/0x1e0 net/socket.c:597
 sock_close+0x16/0x20 net/socket.c:1126
 __fput+0x333/0x7f0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:112
 exit_task_work include/linux/task_work.h:21 [inline]
 do_exit+0xa52/0x1b40 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 get_signal+0x7e8/0x17e0 kernel/signal.c:2334
 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808
 exit_to_usermode_loop+0x224/0x300 arch/x86/entry/common.c:158
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath+0x42f/0x500 arch/x86/entry/common.c:266
 entry_SYSCALL_64_fastpath+0xbc/0xbe
RIP: 0033:0x447299
RSP: 002b:00007f32c314ec08 EFLAGS: 00000282 ORIG_RAX: 000000000000012a
RAX: 0000000000000016 RBX: 000000002001d000 RCX: 0000000000447299
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 000000002001d000
RBP: 0000000000708000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000282 R12: 00000000ffffffff
R13: 0000000000003d10 R14: 00000000006e6dd0 R15: 0000000000000000

Allocated by task 11801:
 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
 __do_kmalloc_node mm/slab.c:3689 [inline]
 __kmalloc_node+0x47/0x70 mm/slab.c:3696
 kmalloc_node include/linux/slab.h:535 [inline]
 kvmalloc_node+0x64/0xd0 mm/util.c:397
 kvmalloc include/linux/mm.h:529 [inline]
 kvzalloc include/linux/mm.h:537 [inline]
 alloc_netdev_mqs+0x16e/0xed0 net/core/dev.c:8018
 tun_set_iff drivers/net/tun.c:2022 [inline]
 __tun_chr_ioctl+0x12be/0x3d20 drivers/net/tun.c:2276
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2521
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1530 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 11801:
 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
 kvfree+0x36/0x60 mm/util.c:416
 netdev_freemem net/core/dev.c:7970 [inline]
 free_netdev+0x2cf/0x360 net/core/dev.c:8132
 tun_set_iff drivers/net/tun.c:2105 [inline]
 __tun_chr_ioctl+0x2cf6/0x3d20 drivers/net/tun.c:2276
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2521
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1530 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 ffff88004f4e08c0
 which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 13320 bytes inside of
 16384-byte region [ffff88004f4e08c0, ffff88004f4e48c0)
The buggy address belongs to the page:
page:ffffea00013d3800 count:1 mapcount:0 mapping:ffff88004f4e08c0 index:0x0 compound_mapcount: 0
flags: 0x500000000008100(slab|head)
raw: 0500000000008100 ffff88004f4e08c0 0000000000000000 0000000100000001
raw: ffffea00013b0220 ffff88006d800c50 ffff88003e802200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88004f4e3b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88004f4e3c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88004f4e3c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff88004f4e3d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88004f4e3d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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