syzbot

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BUG: KASAN: slab-out-of-bounds in __collect_expired_timers include/linux/list.h:729 [inline]
BUG: KASAN: slab-out-of-bounds in collect_expired_timers kernel/time/timer.c:1569 [inline]
BUG: KASAN: slab-out-of-bounds in __run_timers+0xa2e/0xb90 kernel/time/timer.c:1616
Write of size 8 at addr ffff88004c9eba48 by task syz-executor3/23234

CPU: 3 PID: 23234 Comm: syz-executor3 Not tainted 4.14.0-rc1-next-20170918+ #6
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 <IRQ>
 __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
 __collect_expired_timers include/linux/list.h:729 [inline]
 collect_expired_timers kernel/time/timer.c:1569 [inline]
 __run_timers+0xa2e/0xb90 kernel/time/timer.c:1616
 run_timer_softirq+0x4c/0xb0 kernel/time/timer.c:1646
 __do_softirq+0x2bb/0xbd0 kernel/softirq.c:284
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:957
 </IRQ>
 do_softirq.part.20+0x14d/0x190 kernel/softirq.c:328
 do_softirq kernel/softirq.c:176 [inline]
 __local_bh_enable_ip+0x135/0x160 kernel/softirq.c:181
 local_bh_enable include/linux/bottom_half.h:31 [inline]
 tun_rx_batched.isra.43+0x603/0x860 drivers/net/tun.c:1219
 tun_get_user+0x11dd/0x2150 drivers/net/tun.c:1553
 tun_chr_write_iter+0xde/0x190 drivers/net/tun.c:1579
 call_write_iter include/linux/fs.h:1770 [inline]
 new_sync_write fs/read_write.c:468 [inline]
 __vfs_write+0x68a/0x970 fs/read_write.c:481
 vfs_write+0x18f/0x510 fs/read_write.c:543
 SYSC_write fs/read_write.c:588 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:580
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x40c691
RSP: 002b:00007f1e4f648c00 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000004a RCX: 000000000040c691
RDX: 000000000000004a RSI: 0000000020e88000 RDI: 0000000000000015
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000450 R14: 00000000006e3510 R15: 00000000209f4000

Allocated by task 22980:
 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 mm/slab.c:3725 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3734
 kmalloc_array include/linux/slab.h:612 [inline]
 kcalloc include/linux/slab.h:623 [inline]
 __rds_conn_create+0x4cc/0x1870 net/rds/connection.c:176
 rds_conn_create_outgoing+0x3f/0x50 net/rds/connection.c:303
 rds_sendmsg+0xd6c/0x1f90 net/rds/send.c:1112
 sock_sendmsg_nosec net/socket.c:633 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:643
 SYSC_sendto+0x358/0x5a0 net/socket.c:1750
 SyS_sendto+0x40/0x50 net/socket.c:1718
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 22385:
 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 ffff88004c9e8640
 which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 13320 bytes inside of
 16384-byte region [ffff88004c9e8640, ffff88004c9ec640)
The buggy address belongs to the page:
page:ffffea0001327a00 count:1 mapcount:0 mapping:ffff88004c9e8640 index:0x0 compound_mapcount: 0
flags: 0x500000000008100(slab|head)
raw: 0500000000008100 ffff88004c9e8640 0000000000000000 0000000100000001
raw: ffffea00013b6620 ffffea0001362020 ffff88003e802200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88004c9eb900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88004c9eb980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88004c9eba00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff88004c9eba80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88004c9ebb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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