audit: type=1400 audit(1513026500.732:7): avc:  denied  { map } for  pid=3151 comm="syzkaller114050" path="/root/syzkaller114050761" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
==================================================================
BUG: KASAN: double-free or invalid-free in relay_open+0x6a1/0xa40 kernel/relay.c:614

CPU: 1 PID: 3151 Comm: syzkaller114050 Not tainted 4.15.0-rc2-mm1+ #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 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:3492 [inline]
 kfree+0xca/0x250 mm/slab.c:3807
 relay_open+0x6a1/0xa40 kernel/relay.c:614
 do_blk_trace_setup+0x4a4/0xcd0 kernel/trace/blktrace.c:544
 __blk_trace_setup+0xb6/0x140 kernel/trace/blktrace.c:589
 blk_trace_ioctl+0x1d5/0x2a0 kernel/trace/blktrace.c:728
 blkdev_ioctl+0x1845/0x1e00 block/ioctl.c:587
 block_ioctl+0xea/0x130 fs/block_dev.c:1860
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x443e59
RSP: 002b:00007ffc1867fa18 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443e59
RDX: 0000000020f74000 RSI: 00000000c0481273 RDI: 0000000000000003
RBP: 00000000006ce018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000401b40
R13: 0000000000401bd0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 3151:
 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+0x136/0x750 mm/slab.c:3614
 kmalloc include/linux/slab.h:516 [inline]
 kzalloc include/linux/slab.h:705 [inline]
 relay_open+0xf2/0xa40 kernel/relay.c:576
 do_blk_trace_setup+0x4a4/0xcd0 kernel/trace/blktrace.c:544
 __blk_trace_setup+0xb6/0x140 kernel/trace/blktrace.c:589
 blk_trace_ioctl+0x1d5/0x2a0 kernel/trace/blktrace.c:728
 blkdev_ioctl+0x1845/0x1e00 block/ioctl.c:587
 block_ioctl+0xea/0x130 fs/block_dev.c:1860
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 3151:
 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:3492 [inline]
 kfree+0xca/0x250 mm/slab.c:3807
 relay_destroy_channel kernel/relay.c:199 [inline]
 kref_put include/linux/kref.h:70 [inline]
 relay_open+0x84a/0xa40 kernel/relay.c:612
 do_blk_trace_setup+0x4a4/0xcd0 kernel/trace/blktrace.c:544
 __blk_trace_setup+0xb6/0x140 kernel/trace/blktrace.c:589
 blk_trace_ioctl+0x1d5/0x2a0 kernel/trace/blktrace.c:728
 blkdev_ioctl+0x1845/0x1e00 block/ioctl.c:587
 block_ioctl+0xea/0x130 fs/block_dev.c:1860
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96

The buggy address belongs to the object at ffff8801c4f2a040
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8801c4f2a040, ffff8801c4f2a240)
The buggy address belongs to the page:
page:0000000078ec155a count:1 mapcount:0 mapping:00000000d735657c index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c4f2a040 0000000000000000 0000000100000006
raw: ffffea000716f860 ffffea000713cc20 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c4f29f00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801c4f29f80: 00 01 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801c4f2a000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff8801c4f2a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c4f2a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================