linux-kernel - KASAN: out-of-bounds Read in bpf_test

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Message-ID: <0000000000003f78f30570905ed6@google.com>
Date:   Mon, 09 Jul 2018 05:44:02 -0700
From:   syzbot <syzbot+54f39d6ab58f39720a55@...kaller.appspotmail.com>
To:     ast@...nel.org, daniel@...earbox.net, davem@...emloft.net,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: KASAN: out-of-bounds Read in bpf_test_finish

Hello,

syzbot found the following crash on:

HEAD commit:    d90c936fb318 Merge branch 'bpf-nfp-mul-div-support'
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16b88a78400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a501a01deaf0fe9
dashboard link: https://syzkaller.appspot.com/bug?extid=54f39d6ab58f39720a55
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+54f39d6ab58f39720a55@...kaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in _copy_to_user+0xe9/0x110 lib/usercopy.c:27
Read of size 924 at addr ffff880192bffff2 by task syz-executor1/6688

CPU: 1 PID: 6688 Comm: syz-executor1 Not tainted 4.18.0-rc3+ #48
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
  print_address_description+0x6c/0x20b mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
  check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
  kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
  _copy_to_user+0xe9/0x110 lib/usercopy.c:27
  copy_to_user include/linux/uaccess.h:155 [inline]
  bpf_test_finish.isra.7+0xee/0x1f0 net/bpf/test_run.c:59
  bpf_prog_test_run_skb+0x7d7/0xa30 net/bpf/test_run.c:144
  bpf_prog_test_run+0x130/0x1a0 kernel/bpf/syscall.c:1686
  __do_sys_bpf kernel/bpf/syscall.c:2323 [inline]
  __se_sys_bpf kernel/bpf/syscall.c:2267 [inline]
  __x64_sys_bpf+0x3d8/0x510 kernel/bpf/syscall.c:2267
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455e29
Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f95802f1c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f95802f26d4 RCX: 0000000000455e29
RDX: 0000000000000028 RSI: 0000000020000380 RDI: 000000000000000a
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004bbaee R14: 00000000004c8d20 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea00064a8000 count:1 mapcount:1 mapping:ffff8801ceeda041  
index:0x20200 compound_mapcount: 1
flags: 0x2fffc0000048068(uptodate|lru|active|head|swapbacked)
raw: 02fffc0000048068 ffffea0006d642c8 ffffea0006e14288 ffff8801ceeda041
raw: 0000000000020200 0000000000000000 00000001ffffffff ffff8801d285e900
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8801d285e900

Memory state around the buggy address:
  ffff880192c00280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff880192c00300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff880192c00380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                          ^
  ffff880192c00400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff880192c00480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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