Message-ID: <000000000000601367057a095de4@google.com>
Date:   Tue, 06 Nov 2018 17:52:03 -0800
From:   syzbot <syzbot+cbb52e396df3e565ab02@...kaller.appspotmail.com>
To:     cgroups@...r.kernel.org, hannes@...xchg.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        mhocko@...nel.org, syzkaller-bugs@...glegroups.com,
        vdavydov.dev@...il.com
Subject: KASAN: use-after-free Read in get_mem_cgroup_from_mm

Hello,

syzbot found the following crash on:

HEAD commit:    83650fd58a93 Merge tag 'arm64-upstream' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ce682b400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9384ecb1c973baed
dashboard link: https://syzkaller.appspot.com/bug?extid=cbb52e396df3e565ab02
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+cbb52e396df3e565ab02@...kaller.appspotmail.com

FAT-fs (loop1): Unrecognized mount option "." or missing value
F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0)
==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:182  
[inline]
BUG: KASAN: use-after-free in task_css include/linux/cgroup.h:477 [inline]
BUG: KASAN: use-after-free in mem_cgroup_from_task mm/memcontrol.c:815  
[inline]
BUG: KASAN: use-after-free in get_mem_cgroup_from_mm.part.62+0x6d7/0x880  
mm/memcontrol.c:844
Read of size 8 at addr ffff8801c635d210 by task syz-executor0/14887

CPU: 0 PID: 14887 Comm: syz-executor0 Not tainted 4.19.0+ #318
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+0x244/0x39d lib/dump_stack.c:113
  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  __read_once_size include/linux/compiler.h:182 [inline]
  task_css include/linux/cgroup.h:477 [inline]
  mem_cgroup_from_task mm/memcontrol.c:815 [inline]
  get_mem_cgroup_from_mm.part.62+0x6d7/0x880 mm/memcontrol.c:844
  get_mem_cgroup_from_mm mm/memcontrol.c:834 [inline]
  mem_cgroup_try_charge+0x608/0xe20 mm/memcontrol.c:5888
  mcopy_atomic_pte mm/userfaultfd.c:69 [inline]
  mfill_atomic_pte mm/userfaultfd.c:385 [inline]
  __mcopy_atomic mm/userfaultfd.c:529 [inline]
  mcopy_atomic+0xae9/0x2aa0 mm/userfaultfd.c:579
  userfaultfd_copy fs/userfaultfd.c:1690 [inline]
  userfaultfd_ioctl+0x213d/0x54a0 fs/userfaultfd.c:1836
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:509 [inline]
  do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696
  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713
  __do_sys_ioctl fs/ioctl.c:720 [inline]
  __se_sys_ioctl fs/ioctl.c:718 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
Code: fd b3 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f6dd22acc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 0000000020000100 RSI: 00000000c028aa03 RDI: 0000000000000004
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6dd22ad6d4
R13: 00000000004c142b R14: 00000000004d22a8 R15: 00000000ffffffff

Allocated by task 14881:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
  kmem_cache_alloc_node+0x144/0x730 mm/slab.c:3644
  alloc_task_struct_node kernel/fork.c:158 [inline]
  dup_task_struct kernel/fork.c:843 [inline]
  copy_process+0x2026/0x87a0 kernel/fork.c:1751
  _do_fork+0x1cb/0x11d0 kernel/fork.c:2216
  __do_sys_clone kernel/fork.c:2323 [inline]
  __se_sys_clone kernel/fork.c:2317 [inline]
  __x64_sys_clone+0xbf/0x150 kernel/fork.c:2317
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 14881:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
  __cache_free mm/slab.c:3498 [inline]
  kmem_cache_free+0x83/0x290 mm/slab.c:3760
  free_task_struct kernel/fork.c:163 [inline]
  free_task+0x16e/0x1f0 kernel/fork.c:457
  copy_process+0x1dcc/0x87a0 kernel/fork.c:2148
  _do_fork+0x1cb/0x11d0 kernel/fork.c:2216
  __do_sys_clone kernel/fork.c:2323 [inline]
  __se_sys_clone kernel/fork.c:2317 [inline]
  __x64_sys_clone+0xbf/0x150 kernel/fork.c:2317
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801c635c140
  which belongs to the cache task_struct(17:syz0) of size 6080
The buggy address is located 4304 bytes inside of
  6080-byte region [ffff8801c635c140, ffff8801c635d900)
The buggy address belongs to the page:
page:ffffea000718d700 count:1 mapcount:0 mapping:ffff8801ccef9800 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea000573d508 ffffea0006fc6088 ffff8801ccef9800
raw: 0000000000000000 ffff8801c635c140 0000000100000001 ffff880188008ec0
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff880188008ec0

Memory state around the buggy address:
  ffff8801c635d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801c635d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801c635d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                          ^
  ffff8801c635d280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801c635d300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
FAT-fs (loop2): bogus number of FAT structure
FAT-fs (loop2): Can't find a valid FAT filesystem
F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock


---
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