Message-ID: <001a113f9226e3e3ef05626b94f0@google.com>
Date:   Wed, 10 Jan 2018 04:58:02 -0800
From:   syzbot <syzbot+6c15e9744f75f2364773@...kaller.appspotmail.com>
To:     ast@...nel.org, daniel@...earbox.net, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: KASAN: slab-out-of-bounds Read in perf_event_fd_array_release

Hello,

syzkaller hit the following crash on  
b4464bcab38d3f7fe995a7cb960eeac6889bec08
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6c15e9744f75f2364773@...kaller.appspotmail.com
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audit: type=1400 audit(1515566962.610:11): avc:  denied  { map_read  
map_write } for  pid=3488 comm="syzkaller000829"  
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 ffff8801c0055140 by task syzkaller000829/3488

CPU: 0 PID: 3488 Comm: syzkaller000829 Not tainted  
4.15.0-rc7-next-20180110+ #93
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: 00007ffda1715470 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 3488:
  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 1980:
  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 ffff8801c0055040
  which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes to the right of
  256-byte region [ffff8801c0055040, ffff8801c0055140)
The buggy address belongs to the page:
page:ffffea0007001540 count:1 mapcount:0 mapping:ffff8801c0055040 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c0055040 0000000000000000 000000010000000c
raw: ffffea000701e720 ffffea000700c7a0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801c0055000: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
  ffff8801c0055080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff8801c0055100: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                            ^
  ffff8801c0055180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801c0055200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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