linux-kernel - Re: KASAN: use-after-free Read in __list_add

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Date:   Wed, 14 Mar 2018 21:46:01 -0700
From:   syzbot <syzbot+5aef6b1a99035b4b6705@...kaller.appspotmail.com>
To:     dasaratharaman.chandramouli@...el.com, dledford@...hat.com,
        don.hiatt@...el.com, ira.weiny@...el.com, jgg@...pe.ca,
        leonro@...lanox.com, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, markb@...lanox.com, monis@...lanox.com,
        parav@...lanox.com, syzkaller-bugs@...glegroups.com,
        viro@...iv.linux.org.uk
Subject: Re: KASAN: use-after-free Read in __list_add_valid (4)

syzbot has found reproducer for the following crash on upstream commit
3032f8c504d2b15d58e4c96060a96b47e215573c (Wed Mar 14 17:05:59 2018 +0000)
Merge tag 'usb-4.16-rc6' of  
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

So far this crash happened 24 times on upstream.
C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5aef6b1a99035b4b6705@...kaller.appspotmail.com
It will help syzbot understand when the bug is fixed.

audit: type=1400 audit(1521088917.810:6): avc:  denied  { map } for   
pid=4231 comm="bash" path="/bin/bash" dev="sda1" ino=1457  
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
audit: type=1400 audit(1521088924.156:7): avc:  denied  { map } for   
pid=4245 comm="syzkaller618201" path="/root/syzkaller618201737" dev="sda1"  
ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
==================================================================
BUG: KASAN: use-after-free in __list_add_valid+0xc6/0xd0 lib/list_debug.c:26
Read of size 8 at addr ffff8801ae29c218 by task syzkaller618201/4248

CPU: 1 PID: 4248 Comm: syzkaller618201 Not tainted 4.16.0-rc5+ #353
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_add_valid+0xc6/0xd0 lib/list_debug.c:26
  __list_add include/linux/list.h:60 [inline]
  list_add_tail include/linux/list.h:93 [inline]
  cma_listen_on_all drivers/infiniband/core/cma.c:2309 [inline]
  rdma_listen+0x581/0x8e0 drivers/infiniband/core/cma.c:3331
  ucma_listen+0x172/0x1f0 drivers/infiniband/core/ucma.c:1064
  ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1633
  __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_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441859
RSP: 002b:00007ffec59ea058 EFLAGS: 00000207 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441859
RDX: 000000000000003a RSI: 0000000020000100 RDI: 0000000000000003
RBP: 000000000000717f R08: 00007ffec59ea218 R09: 00007ffec59ea218
R10: 00007ffec59ea218 R11: 0000000000000207 R12: 0000000000000000
R13: 00000000006cd448 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4246:
  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:1633
  __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_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 4246:
  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:1712
  __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
  SYSC_exit_group kernel/exit.c:979 [inline]
  SyS_exit_group+0x1d/0x20 kernel/exit.c:977
  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801ae29c040
  which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 472 bytes inside of
  1024-byte region [ffff8801ae29c040, ffff8801ae29c440)
The buggy address belongs to the page:
page:ffffea0006b8a700 count:1 mapcount:0 mapping:ffff8801ae29c040 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801ae29c040 0000000000000000 0000000100000007
raw: ffffea0006c11120 ffffea0006c15d20 ffff8801dac00ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801ae29c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801ae29c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801ae29c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                             ^
  ffff8801ae29c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801ae29c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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