Subject: KASAN: slab-out-of-bounds Read in pfkey_add

From: syzbot <[email-masked]>
Date: Fri, 15 Dec 2017 23:51:01 -0800

Hello,

syzkaller hit the following crash on  
50c4c4e268a2d7a3e58ebb698ac74da0de40ae36
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.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

audit: type=1400 audit(1513021744.055:7): avc:  denied  { map } for   
pid=3149 comm="syzkaller428285" path="/root/syzkaller428285483" 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: slab-out-of-bounds in memcpy include/linux/string.h:341 [inline]
BUG: KASAN: slab-out-of-bounds in pfkey_msg2xfrm_state  
net/key/af_key.c:1212 [inline]
BUG: KASAN: slab-out-of-bounds in pfkey_add+0x1634/0x3270  
net/key/af_key.c:1491
Read of size 8192 at addr ffff8801c5197318 by task syzkaller428285/3149

CPU: 0 PID: 3149 Comm: syzkaller428285 Not tainted 4.15.0-rc3+ #127
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:252
  kasan_report_error mm/kasan/report.c:351 [inline]
  kasan_report+0x25b/0x340 mm/kasan/report.c:409
  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
  check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
  memcpy+0x23/0x50 mm/kasan/kasan.c:302
  memcpy include/linux/string.h:341 [inline]
  pfkey_msg2xfrm_state net/key/af_key.c:1212 [inline]
  pfkey_add+0x1634/0x3270 net/key/af_key.c:1491
  pfkey_process+0x60b/0x720 net/key/af_key.c:2809
  pfkey_sendmsg+0x4d6/0x9f0 net/key/af_key.c:3648
  sock_sendmsg_nosec net/socket.c:636 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:646
  ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2026
  __sys_sendmsg+0xe5/0x210 net/socket.c:2060
  C_SYSC_sendmsg net/compat.c:739 [inline]
  compat_SyS_sendmsg+0x2a/0x40 net/compat.c:737
  do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
  do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125
RIP: 0023:0xf7fd4c79
RSP: 002b:00000000ff9d7c1c EFLAGS: 00000203 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000205f5000
RDX: 0000000000000000 RSI: 0000000000000167 RDI: 000000000000000f
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 3149:
  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:551
  __do_kmalloc_node mm/slab.c:3675 [inline]
  __kmalloc_node_track_caller+0x47/0x70 mm/slab.c:3689
  __kmalloc_reserve.isra.41+0x41/0xd0 net/core/skbuff.c:137
  __alloc_skb+0x13b/0x780 net/core/skbuff.c:205
  alloc_skb include/linux/skbuff.h:983 [inline]
  pfkey_sendmsg+0x20f/0x9f0 net/key/af_key.c:3635
  sock_sendmsg_nosec net/socket.c:636 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:646
  ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2026
  __sys_sendmsg+0xe5/0x210 net/socket.c:2060
  C_SYSC_sendmsg net/compat.c:739 [inline]
  compat_SyS_sendmsg+0x2a/0x40 net/compat.c:737
  do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
  do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125

Freed by task 1636:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
  set_track mm/kasan/kasan.c:459 [inline]
  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
  __cache_free mm/slab.c:3491 [inline]
  kfree+0xca/0x250 mm/slab.c:3806
  kernfs_fop_release+0x13f/0x180 fs/kernfs/file.c:783
  __fput+0x333/0x7f0 fs/file_table.c:210
  ____fput+0x15/0x20 fs/file_table.c:244
  task_work_run+0x199/0x270 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:191 [inline]
  exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162
  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+0x94/0x96

The buggy address belongs to the object at ffff8801c5197300
  which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
  512-byte region [ffff8801c5197300, ffff8801c5197500)
The buggy address belongs to the page:
page:00000000ea98bd6b count:1 mapcount:0 mapping:000000003ab76c13 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c5197080 0000000000000000 0000000100000006
raw: ffffea0007146520 ffffea0007147960 ffff8801db000940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801c5197400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff8801c5197480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff8801c5197500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                    ^
  ffff8801c5197580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801c5197600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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