Message-ID: <001a1144966ac62d2705670c672c@google.com>
Date:   Sat, 10 Mar 2018 02:31:01 -0800
From:   syzbot <syzbot+09e05aba06723a94d43d@...kaller.appspotmail.com>
To:     arve@...roid.com, dasaratharaman.chandramouli@...el.com,
        devel@...verdev.osuosl.org, dledford@...hat.com,
        gregkh@...uxfoundation.org, jgg@...pe.ca, leonro@...lanox.com,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        maco@...roid.com, markb@...lanox.com, monis@...lanox.com,
        parav@...lanox.com, syzkaller-bugs@...glegroups.com,
        tkjos@...roid.com
Subject: Re: KASAN: use-after-free Read in __list_del_entry_valid (3)

syzbot has found reproducer for the following crash on upstream commit
cdb06e9d8f520c969676e7d6778cffe5894f079f (Sat Mar 10 00:59:19 2018 +0000)
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

So far this crash happened 5 times on upstream.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.
user-space arch: i386

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+09e05aba06723a94d43d@...kaller.appspotmail.com
It will help syzbot understand when the bug is fixed.

audit: type=1400 audit(1520677624.558:8): avc:  denied  { map } for   
pid=4244 comm="syz-execprog" path="/root/syzkaller-shm785876307" dev="sda1"  
ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=unconfined_u:object_r:file_t:s0 tclass=file permissive=1
IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0x144/0x150  
lib/list_debug.c:54
Read of size 8 at addr ffff8801cde96ae0 by task syz-executor0/4261

CPU: 0 PID: 4261 Comm: syz-executor0 Not tainted 4.16.0-rc4+ #258
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+0x194/0x24d 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+0x23c/0x360 mm/kasan/report.c:412
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  __list_del_entry_valid+0x144/0x150 lib/list_debug.c:54
  __list_del_entry include/linux/list.h:117 [inline]
  list_del include/linux/list.h:125 [inline]
  cma_cancel_listens drivers/infiniband/core/cma.c:1569 [inline]
  cma_cancel_operation+0x455/0xd60 drivers/infiniband/core/cma.c:1597
  rdma_destroy_id+0xff/0xda0 drivers/infiniband/core/cma.c:1661
  ucma_close+0x100/0x2f0 drivers/infiniband/core/ucma.c:1706
  __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:865
  do_group_exit+0x149/0x400 kernel/exit.c:968
  get_signal+0x73a/0x16d0 kernel/signal.c:2469
  do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809
  exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
  do_syscall_32_irqs_on arch/x86/entry/common.c:336 [inline]
  do_fast_syscall_32+0xbe6/0xf9f arch/x86/entry/common.c:392
  entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f93c99
RSP: 002b:00000000f7f6e10c EFLAGS: 00000296 ORIG_RAX: 00000000000000f0
RAX: fffffffffffffe00 RBX: 000000000813af98 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4258:
  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
  kmem_cache_alloc_trace+0x136/0x740 mm/slab.c:3607
  kmalloc include/linux/slab.h:512 [inline]
  kzalloc include/linux/slab.h:701 [inline]
  rdma_create_id+0xd0/0x630 drivers/infiniband/core/cma.c:787
  ucma_create_id+0x31a/0x620 drivers/infiniband/core/ucma.c:479
  ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1627
  __vfs_write+0xef/0x970 fs/read_write.c:480
  vfs_write+0x189/0x510 fs/read_write.c:544
  SYSC_write fs/read_write.c:589 [inline]
  SyS_write+0xef/0x220 fs/read_write.c:581
  do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
  do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
  entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 4261:
  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
  rdma_destroy_id+0x821/0xda0 drivers/infiniband/core/cma.c:1691
  ucma_close+0x100/0x2f0 drivers/infiniband/core/ucma.c:1706
  __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:865
  do_group_exit+0x149/0x400 kernel/exit.c:968
  get_signal+0x73a/0x16d0 kernel/signal.c:2469
  do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809
  exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
  do_syscall_32_irqs_on arch/x86/entry/common.c:336 [inline]
  do_fast_syscall_32+0xbe6/0xf9f arch/x86/entry/common.c:392
  entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

The buggy address belongs to the object at ffff8801cde96900
  which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 480 bytes inside of
  1024-byte region [ffff8801cde96900, ffff8801cde96d00)
The buggy address belongs to the page:
page:ffffea000737a580 count:1 mapcount:0 mapping:ffff8801cde96000 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801cde96000 0000000000000000 0000000100000007
raw: ffffea0006a8e720 ffff8801dac01848 ffff8801dac00ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801cde96980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801cde96a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801cde96a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                        ^
  ffff8801cde96b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801cde96b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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