Subject: KASAN: use-after-free Read in __xfrm_state_lookup

From: syzbot <[email-masked]>
Date: Wed, 01 Nov 2017 10:55:01 -0700

Hello,

syzkaller hit the following crash on  
33ad61d0f799656e8987e9c80e6e15151bb857f3
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.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

==================================================================
BUG: KASAN: use-after-free in __xfrm_state_lookup+0x695/0x6b0  
net/xfrm/xfrm_state.c:833
Read of size 4 at addr ffff8801d434e538 by task syzkaller647520/2991

CPU: 1 PID: 2991 Comm: syzkaller647520 Not tainted 4.14.0-rc5+ #89
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  <IRQ>
  __dump_stack lib/dump_stack.c:16 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:52
  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
  __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
  __xfrm_state_lookup+0x695/0x6b0 net/xfrm/xfrm_state.c:833
  xfrm_state_lookup+0x8a/0x160 net/xfrm/xfrm_state.c:1592
  xfrm_input+0x8e5/0x22f0 net/xfrm/xfrm_input.c:302
  xfrm6_rcv_spi net/ipv6/xfrm6_input.c:30 [inline]
  xfrm6_rcv_tnl+0x168/0x1d0 net/ipv6/xfrm6_input.c:64
  xfrm6_rcv+0x17/0x20 net/ipv6/xfrm6_input.c:71
  xfrm6_ah_rcv+0x166/0x300 net/ipv6/xfrm6_protocol.c:101
  ip6_input_finish+0x36f/0x1700 net/ipv6/ip6_input.c:284
  NF_HOOK include/linux/netfilter.h:249 [inline]
  ip6_input+0xe9/0x560 net/ipv6/ip6_input.c:327
  dst_input include/net/dst.h:465 [inline]
  ip6_rcv_finish+0x1a9/0x7a0 net/ipv6/ip6_input.c:71
  NF_HOOK include/linux/netfilter.h:249 [inline]
  ipv6_rcv+0xf28/0x1f80 net/ipv6/ip6_input.c:208
  __netif_receive_skb_core+0x1a3e/0x34b0 net/core/dev.c:4477
  __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4542
  process_backlog+0x203/0x740 net/core/dev.c:5221
  napi_poll net/core/dev.c:5619 [inline]
  net_rx_action+0x792/0x1910 net/core/dev.c:5685
  __do_softirq+0x2d7/0xb85 kernel/softirq.c:284
  do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:957
  </IRQ>
  do_softirq.part.22+0x14d/0x190 kernel/softirq.c:328
  do_softirq kernel/softirq.c:176 [inline]
  __local_bh_enable_ip+0x135/0x160 kernel/softirq.c:181
  local_bh_enable include/linux/bottom_half.h:31 [inline]
  rcu_read_unlock_bh include/linux/rcupdate.h:727 [inline]
  ip6_finish_output2+0xb26/0x22a0 net/ipv6/ip6_output.c:121
  ip6_finish_output+0x2f9/0x920 net/ipv6/ip6_output.c:146
  NF_HOOK_COND include/linux/netfilter.h:238 [inline]
  ip6_output+0x1f4/0x850 net/ipv6/ip6_output.c:163
  dst_output include/net/dst.h:459 [inline]
  ip6_local_out+0x95/0x160 net/ipv6/output_core.c:176
  ip6_send_skb+0xa1/0x330 net/ipv6/ip6_output.c:1658
  ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1678
  rawv6_push_pending_frames net/ipv6/raw.c:616 [inline]
  rawv6_sendmsg+0x2eb9/0x3e40 net/ipv6/raw.c:935
  inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
  sock_sendmsg_nosec net/socket.c:633 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:643
  SYSC_sendto+0x352/0x5a0 net/socket.c:1750
  SyS_sendto+0x40/0x50 net/socket.c:1718
  entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x4467c9
RSP: 002b:00007f93ea848cf8 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004467c9
RDX: 00000000000007f1 RSI: 000000002013b7ff RDI: 0000000000000003
RBP: 0000000000000000 R08: 00000000204e8fe4 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 00007ffca6cb535f R14: 00007f93ea8499c0 R15: 0000000000000000

Allocated by task 2989:
  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
  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:3689 [inline]
  __kmalloc_node_track_caller+0x47/0x70 mm/slab.c:3703
  __kmalloc_reserve.isra.40+0x41/0xd0 net/core/skbuff.c:138
  __alloc_skb+0x13b/0x780 net/core/skbuff.c:206
  alloc_skb include/linux/skbuff.h:985 [inline]
  sock_wmalloc+0x140/0x1d0 net/core/sock.c:1932
  __ip6_append_data.isra.43+0x2681/0x3340 net/ipv6/ip6_output.c:1397
  ip6_append_data+0x189/0x290 net/ipv6/ip6_output.c:1552
  rawv6_sendmsg+0x1dd9/0x3e40 net/ipv6/raw.c:928
  inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
  sock_sendmsg_nosec net/socket.c:633 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:643
  SYSC_sendto+0x352/0x5a0 net/socket.c:1750
  SyS_sendto+0x40/0x50 net/socket.c:1718
  entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 2991:
  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
  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:3503 [inline]
  kfree+0xca/0x250 mm/slab.c:3820
  skb_free_head+0x74/0xb0 net/core/skbuff.c:554
  pskb_expand_head+0x36b/0x1210 net/core/skbuff.c:1494
  __pskb_pull_tail+0x14a/0x17c0 net/core/skbuff.c:1877
  pskb_may_pull include/linux/skbuff.h:2102 [inline]
  xfrm_parse_spi+0x3d3/0x4d0 net/xfrm/xfrm_input.c:170
  xfrm_input+0xce2/0x22f0 net/xfrm/xfrm_input.c:291
  xfrm6_rcv_spi net/ipv6/xfrm6_input.c:30 [inline]
  xfrm6_rcv_tnl+0x168/0x1d0 net/ipv6/xfrm6_input.c:64
  xfrm6_rcv+0x17/0x20 net/ipv6/xfrm6_input.c:71
  xfrm6_ah_rcv+0x166/0x300 net/ipv6/xfrm6_protocol.c:101
  ip6_input_finish+0x36f/0x1700 net/ipv6/ip6_input.c:284
  NF_HOOK include/linux/netfilter.h:249 [inline]
  ip6_input+0xe9/0x560 net/ipv6/ip6_input.c:327
  dst_input include/net/dst.h:465 [inline]
  ip6_rcv_finish+0x1a9/0x7a0 net/ipv6/ip6_input.c:71
  NF_HOOK include/linux/netfilter.h:249 [inline]
  ipv6_rcv+0xf28/0x1f80 net/ipv6/ip6_input.c:208
  __netif_receive_skb_core+0x1a3e/0x34b0 net/core/dev.c:4477
  __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4542
  process_backlog+0x203/0x740 net/core/dev.c:5221
  napi_poll net/core/dev.c:5619 [inline]
  net_rx_action+0x792/0x1910 net/core/dev.c:5685
  __do_softirq+0x2d7/0xb85 kernel/softirq.c:284

The buggy address belongs to the object at ffff8801d434e500
  which belongs to the cache kmalloc-512 of size 512
The buggy address is located 56 bytes inside of
  512-byte region [ffff8801d434e500, ffff8801d434e700)
The buggy address belongs to the page:
page:ffffea000750d380 count:1 mapcount:0 mapping:ffff8801d434e000 index:0x0

---
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See https://goo.gl/tpsmEJ for details.
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