syzbot

audit: type=1400 audit(1515708029.662:11): avc:  denied  { map_read map_write } for  pid=3506 comm="syzkaller623626" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf permissive=1
==================================================================
BUG: KASAN: slab-out-of-bounds in __read_once_size include/linux/compiler.h:188 [inline]
BUG: KASAN: slab-out-of-bounds in perf_event_fd_array_release+0x435/0x480 kernel/bpf/arraymap.c:544
Read of size 8 at addr ffff8801cbc7e740 by task syzkaller623626/3506

CPU: 0 PID: 3506 Comm: syzkaller623626 Not tainted 4.15.0-rc7-next-20180111+ #94
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_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __read_once_size include/linux/compiler.h:188 [inline]
 perf_event_fd_array_release+0x435/0x480 kernel/bpf/arraymap.c:544
 bpf_map_release+0x84/0xc0 kernel/bpf/syscall.c:257
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:869
 do_group_exit+0x149/0x400 kernel/exit.c:972
 SYSC_exit_group kernel/exit.c:983 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:981
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x440a69
RSP: 002b:00000000007dff48 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fff81d9f6b0 RCX: 0000000000440a69
RDX: 0000000000440a69 RSI: 000000000000002c RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000402240
R13: 00000000004022d0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 3506:
 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:552
 __do_kmalloc_node mm/slab.c:3669 [inline]
 __kmalloc_node+0x47/0x70 mm/slab.c:3676
 kmalloc_node include/linux/slab.h:557 [inline]
 bpf_map_area_alloc+0x32/0x80 kernel/bpf/syscall.c:123
 array_map_alloc+0x351/0xa00 kernel/bpf/arraymap.c:96
 fd_array_map_alloc+0x57/0x70 kernel/bpf/arraymap.c:341
 find_and_alloc_map kernel/bpf/syscall.c:105 [inline]
 map_create kernel/bpf/syscall.c:404 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1805 [inline]
 SyS_bpf+0x7f8/0x4400 kernel/bpf/syscall.c:1782
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 1848:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd9/0x260 mm/slab.c:3800
 seq_release fs/seq_file.c:366 [inline]
 single_release+0x80/0xb0 fs/seq_file.c:602
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0

The buggy address belongs to the object at ffff8801cbc7e640
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes to the right of
 256-byte region [ffff8801cbc7e640, ffff8801cbc7e740)
The buggy address belongs to the page:
page:ffffea00072f1f80 count:1 mapcount:0 mapping:ffff8801cbc7e000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801cbc7e000 0000000000000000 000000010000000c
raw: ffffea00072f1e60 ffffea00072f41a0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cbc7e600: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff8801cbc7e680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801cbc7e700: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                           ^
 ffff8801cbc7e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cbc7e800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================