netlink: 12 bytes leftover after parsing attributes in process `syz-executor2'.
==================================================================
BUG: KASAN: use-after-free in disk_unblock_events+0x51/0x60 block/genhd.c:1632
Read of size 8 at addr ffff880198cd9a80 by task syz-executor1/27652

CPU: 1 PID: 27652 Comm: syz-executor1 Not tainted 4.14.0-rc7+ #156
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_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 disk_unblock_events+0x51/0x60 block/genhd.c:1632
 __blkdev_get+0x78d/0xf90 fs/block_dev.c:1547
 blkdev_get+0x3a1/0xad0 fs/block_dev.c:1603
 blkdev_open+0x1c9/0x250 fs/block_dev.c:1761
 do_dentry_open+0x664/0xd40 fs/open.c:752
 vfs_open+0x107/0x220 fs/open.c:866
 do_last fs/namei.c:3387 [inline]
 path_openat+0x1151/0x3520 fs/namei.c:3527
 do_filp_open+0x25b/0x3b0 fs/namei.c:3562
 do_sys_open+0x502/0x6d0 fs/open.c:1059
 SYSC_open fs/open.c:1077 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1072
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x40cba1
RSP: 002b:00007fe477641710 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: cccccccccccccccd RCX: 000000000040cba1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fe4776417c0
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000202a0000 R11: 0000000000000293 R12: 00000000006f43b8
R13: 00000000ffffffff R14: 00007fe4776426d4 R15: 0000000000000000

Allocated by task 26448:
 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_node_trace+0x150/0x750 mm/slab.c:3670
 kmalloc_node include/linux/slab.h:531 [inline]
 kzalloc_node include/linux/slab.h:677 [inline]
 alloc_disk_node+0xb4/0x4e0 block/genhd.c:1375
 alloc_disk+0x18/0x20 block/genhd.c:1359
 loop_add+0x45c/0xa50 drivers/block/loop.c:1795
 loop_control_ioctl+0x129/0x490 drivers/block/loop.c:1927
 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 27652:
 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
 disk_release+0x327/0x410 block/genhd.c:1218
 device_release+0x7c/0x200 drivers/base/core.c:814
 kobject_cleanup lib/kobject.c:648 [inline]
 kobject_release lib/kobject.c:677 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x14c/0x240 lib/kobject.c:694
 put_disk+0x23/0x30 block/genhd.c:1440
 __blkdev_get+0x6ed/0xf90 fs/block_dev.c:1540
 blkdev_get+0x3a1/0xad0 fs/block_dev.c:1603
 blkdev_open+0x1c9/0x250 fs/block_dev.c:1761
 do_dentry_open+0x664/0xd40 fs/open.c:752
 vfs_open+0x107/0x220 fs/open.c:866
 do_last fs/namei.c:3387 [inline]
 path_openat+0x1151/0x3520 fs/namei.c:3527
 do_filp_open+0x25b/0x3b0 fs/namei.c:3562
 do_sys_open+0x502/0x6d0 fs/open.c:1059
 SYSC_open fs/open.c:1077 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1072
 entry_SYSCALL_64_fastpath+0x1f/0xbe

The buggy address belongs to the object at ffff880198cd9500
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1408 bytes inside of
 2048-byte region [ffff880198cd9500, ffff880198cd9d00)
The buggy address belongs to the page:
page:ffffea0006633600 count:1 mapcount:0 mapping:ffff880198cd8400 index:0x0 compound_mapcount: 0
flags: 0x200000000008100(slab|head)
raw: 0200000000008100 ffff880198cd8400 0000000000000000 0000000100000003
raw: ffffea0007100420 ffffea0007287d20 ffff8801dac00c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880198cd9980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880198cd9a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff880198cd9a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff880198cd9b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880198cd9b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================