audit: type=1400 audit(1514421813.959:7): avc:  denied  { map } for  pid=3157 comm="syzkaller826623" path="/root/syzkaller826623437" 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: 0 PID: 3157 Comm: syzkaller826623 Not tainted 4.15.0-rc4-mm1+ #49
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:256
 kasan_report_double_free+0x55/0x80 mm/kasan/report.c:337
 kasan_slab_free+0xa3/0xc0 mm/kasan/kasan.c:514
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd6/0x260 mm/slab.c:3800
 relay_open+0x6a1/0xa40 kernel/relay.c:614
 do_blk_trace_setup+0x4a4/0xcd0 kernel/trace/blktrace.c:544
 __blk_trace_setup+0xbe/0x150 kernel/trace/blktrace.c:589
 blk_trace_setup+0x4d/0x70 kernel/trace/blktrace.c:607
 sg_ioctl+0xc71/0x2d90 drivers/scsi/sg.c:1089
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 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: 0033:0x443de9
RSP: 002b:00007ffe6b5ec978 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443de9
RDX: 0000000020001f8a RSI: 00000000c0481273 RDI: 0000000000000003
RBP: 00000000006ce018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000401ad0
R13: 0000000000401b60 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 3157:
 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:3607
 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+0xbe/0x150 kernel/trace/blktrace.c:589
 blk_trace_setup+0x4d/0x70 kernel/trace/blktrace.c:607
 sg_ioctl+0xc71/0x2d90 drivers/scsi/sg.c:1089
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 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 3157:
 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:3485 [inline]
 kfree+0xd6/0x260 mm/slab.c:3800
 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+0xbe/0x150 kernel/trace/blktrace.c:589
 blk_trace_setup+0x4d/0x70 kernel/trace/blktrace.c:607
 sg_ioctl+0xc71/0x2d90 drivers/scsi/sg.c:1089
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 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 ffff8801cc749340
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8801cc749340, ffff8801cc749540)
The buggy address belongs to the page:
page:ffffea000731d240 count:1 mapcount:0 mapping:ffff8801cc7490c0 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801cc7490c0 0000000000000000 0000000100000006
raw: ffffea0007246f60 ffffea0007246de0 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cc749200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cc749280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8801cc749300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff8801cc749380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cc749400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================