BUG: KASAN: use-after-free in atomic_long_read include/linux/compiler.h:276 [inline]
BUG: KASAN: use-after-free in packet_getsockopt+0xc72/0xe00 net/packet/af_packet.c:3932
Read of size 8 at addr ffff88003d316798 by task syz-executor0/3012

CPU: 3 PID: 3012 Comm: syz-executor0 Not tainted 4.14.0-rc5-next-20171018+ #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 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
 atomic_long_read include/linux/compiler.h:276 [inline]
 packet_getsockopt+0xc72/0xe00 net/packet/af_packet.c:3932
 SYSC_getsockopt net/socket.c:1882 [inline]
 SyS_getsockopt+0x178/0x340 net/socket.c:1864
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x447c89
RSP: 002b:00007f48262e6bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007f48262e76cc RCX: 0000000000447c89
RDX: 0000000000000015 RSI: 0000000000000107 RDI: 0000000000000011
RBP: 0000000000000082 R08: 00000000208a5000 R09: 0000000000000000
R10: 0000000020ec8000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f48262e79c0 R15: 00007f48262e7700

Allocated by task 3011:
 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
 kzalloc include/linux/slab.h:502 [inline]
 fanout_add+0x27e/0x1480 net/packet/af_packet.c:1692
 packet_setsockopt+0xfdc/0x1e80 net/packet/af_packet.c:3803
 SYSC_setsockopt net/socket.c:1851 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1830
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 3011:
 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
 fanout_add+0x432/0x1480 net/packet/af_packet.c:1770
 packet_setsockopt+0xfdc/0x1e80 net/packet/af_packet.c:3803
 SYSC_setsockopt net/socket.c:1851 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1830
 entry_SYSCALL_64_fastpath+0x1f/0xbe

The buggy address belongs to the object at ffff88003d316780
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 128-byte region [ffff88003d316780, ffff88003d316800)
The buggy address belongs to the page:
page:ffffea0000f4c580 count:1 mapcount:0 mapping:ffff88003d316000 index:0x0
flags: 0x100000000000100(slab)
raw: 0100000000000100 ffff88003d316000 0000000000000000 0000000100000015
raw: ffffea0000f54a60 ffffea0000f23320 ffff88003e800640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88003d316680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff88003d316700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88003d316780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88003d316800: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff88003d316880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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