syzbot

kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
==================================================================
BUG: KASAN: use-after-free in __collect_expired_timers include/linux/list.h:729 [inline]
BUG: KASAN: use-after-free in collect_expired_timers kernel/time/timer.c:1569 [inline]
BUG: KASAN: use-after-free in __run_timers+0xa2e/0xb90 kernel/time/timer.c:1616
Write of size 8 at addr ffff8800380ebac8 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.13.0-next-20170913+ #3
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
 invoke_softirq kernel/softirq.c:364 [inline]
 irq_exit+0x1d3/0x210 kernel/softirq.c:405
 exiting_irq arch/x86/include/asm/apic.h:638 [inline]
 smp_apic_timer_interrupt+0x177/0x710 arch/x86/kernel/apic/apic.c:1048
 apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:577
 </IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
RSP: 0018:ffffffff85a07d10 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
RAX: dffffc0000000000 RBX: 1ffffffff0b40fa5 RCX: 0000000000000000
RDX: 1ffffffff0b59308 RSI: 0000000000000001 RDI: ffffffff85ac9840
RBP: ffffffff85a07d10 R08: ffffffff8161b619 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85ac9830
R13: ffffffff85a07dc8 R14: 0000000000000000 R15: ffffffff85a2f380
 arch_safe_halt arch/x86/include/asm/paravirt.h:98 [inline]
 default_idle+0xbf/0x460 arch/x86/kernel/process.c:341
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:332
 default_idle_call+0x36/0x90 kernel/sched/idle.c:98
 cpuidle_idle_call kernel/sched/idle.c:156 [inline]
 do_idle+0x256/0x3b0 kernel/sched/idle.c:246
 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351
 rest_init+0xed/0xf0 init/main.c:435
 start_kernel+0x72e/0x754 init/main.c:710
 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:377
 x86_64_start_kernel+0x87/0x8a arch/x86/kernel/head64.c:358
 secondary_startup_64+0xa5/0xa5 arch/x86/kernel/head_64.S:235

Allocated by task 13187:
 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 13187:
 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 ffff8800380e86c0
 which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 13320 bytes inside of
 16384-byte region [ffff8800380e86c0, ffff8800380ec6c0)
The buggy address belongs to the page:
page:ffffea0000e03a00 count:1 mapcount:0 mapping:ffff8800380e86c0 index:0xffff8800380e86c0 compound_mapcount: 0
flags: 0x100000000008100(slab|head)
raw: 0100000000008100 ffff8800380e86c0 ffff8800380e86c0 0000000100000000
raw: ffffea0000e5b220 ffff88003e801c60 ffff88003e802200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8800380eb980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8800380eba00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8800380eba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8800380ebb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8800380ebb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================