queue-4.4/xfrm_user-prevent-leaking-2-bytes-of-kernel-memory.patch

   1 From 45c180bc29babbedd6b8c01b975780ef44d9d09c Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Mon, 18 Jun 2018 21:35:07 -0700
   4 Subject: xfrm_user: prevent leaking 2 bytes of kernel memory
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8 commit 45c180bc29babbedd6b8c01b975780ef44d9d09c upstream.
   9
  10 struct xfrm_userpolicy_type has two holes, so we should not
  11 use C99 style initializer.
  12
  13 KMSAN report:
  14
  15 BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
  16 BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x1b14/0x2800 lib/iov_iter.c:571
  17 CPU: 1 PID: 4520 Comm: syz-executor841 Not tainted 4.17.0+ #5
  18 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  19 Call Trace:
  20  __dump_stack lib/dump_stack.c:77 [inline]
  21  dump_stack+0x185/0x1d0 lib/dump_stack.c:113
  22  kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1117
  23  kmsan_internal_check_memory+0x138/0x1f0 mm/kmsan/kmsan.c:1211
  24  kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1253
  25  copyout lib/iov_iter.c:140 [inline]
  26  _copy_to_iter+0x1b14/0x2800 lib/iov_iter.c:571
  27  copy_to_iter include/linux/uio.h:106 [inline]
  28  skb_copy_datagram_iter+0x422/0xfa0 net/core/datagram.c:431
  29  skb_copy_datagram_msg include/linux/skbuff.h:3268 [inline]
  30  netlink_recvmsg+0x6f1/0x1900 net/netlink/af_netlink.c:1959
  31  sock_recvmsg_nosec net/socket.c:802 [inline]
  32  sock_recvmsg+0x1d6/0x230 net/socket.c:809
  33  ___sys_recvmsg+0x3fe/0x810 net/socket.c:2279
  34  __sys_recvmmsg+0x58e/0xe30 net/socket.c:2391
  35  do_sys_recvmmsg+0x2a6/0x3e0 net/socket.c:2472
  36  __do_sys_recvmmsg net/socket.c:2485 [inline]
  37  __se_sys_recvmmsg net/socket.c:2481 [inline]
  38  __x64_sys_recvmmsg+0x15d/0x1c0 net/socket.c:2481
  39  do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
  40  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  41 RIP: 0033:0x446ce9
  42 RSP: 002b:00007fc307918db8 EFLAGS: 00000293 ORIG_RAX: 000000000000012b
  43 RAX: ffffffffffffffda RBX: 00000000006dbc24 RCX: 0000000000446ce9
  44 RDX: 000000000000000a RSI: 0000000020005040 RDI: 0000000000000003
  45 RBP: 00000000006dbc20 R08: 0000000020004e40 R09: 0000000000000000
  46 R10: 0000000040000000 R11: 0000000000000293 R12: 0000000000000000
  47 R13: 00007ffc8d2df32f R14: 00007fc3079199c0 R15: 0000000000000001
  48
  49 Uninit was stored to memory at:
  50  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
  51  kmsan_save_stack mm/kmsan/kmsan.c:294 [inline]
  52  kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:685
  53  kmsan_memcpy_origins+0x11d/0x170 mm/kmsan/kmsan.c:527
  54  __msan_memcpy+0x109/0x160 mm/kmsan/kmsan_instr.c:413
  55  __nla_put lib/nlattr.c:569 [inline]
  56  nla_put+0x276/0x340 lib/nlattr.c:627
  57  copy_to_user_policy_type net/xfrm/xfrm_user.c:1678 [inline]
  58  dump_one_policy+0xbe1/0x1090 net/xfrm/xfrm_user.c:1708
  59  xfrm_policy_walk+0x45a/0xd00 net/xfrm/xfrm_policy.c:1013
  60  xfrm_dump_policy+0x1c0/0x2a0 net/xfrm/xfrm_user.c:1749
  61  netlink_dump+0x9b5/0x1550 net/netlink/af_netlink.c:2226
  62  __netlink_dump_start+0x1131/0x1270 net/netlink/af_netlink.c:2323
  63  netlink_dump_start include/linux/netlink.h:214 [inline]
  64  xfrm_user_rcv_msg+0x8a3/0x9b0 net/xfrm/xfrm_user.c:2577
  65  netlink_rcv_skb+0x37e/0x600 net/netlink/af_netlink.c:2448
  66  xfrm_netlink_rcv+0xb2/0xf0 net/xfrm/xfrm_user.c:2598
  67  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  68  netlink_unicast+0x1680/0x1750 net/netlink/af_netlink.c:1336
  69  netlink_sendmsg+0x104f/0x1350 net/netlink/af_netlink.c:1901
  70  sock_sendmsg_nosec net/socket.c:629 [inline]
  71  sock_sendmsg net/socket.c:639 [inline]
  72  ___sys_sendmsg+0xec8/0x1320 net/socket.c:2117
  73  __sys_sendmsg net/socket.c:2155 [inline]
  74  __do_sys_sendmsg net/socket.c:2164 [inline]
  75  __se_sys_sendmsg net/socket.c:2162 [inline]
  76  __x64_sys_sendmsg+0x331/0x460 net/socket.c:2162
  77  do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
  78  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  79 Local variable description: ----upt.i@dump_one_policy
  80 Variable was created at:
  81  dump_one_policy+0x78/0x1090 net/xfrm/xfrm_user.c:1689
  82  xfrm_policy_walk+0x45a/0xd00 net/xfrm/xfrm_policy.c:1013
  83
  84 Byte 130 of 137 is uninitialized
  85 Memory access starts at ffff88019550407f
  86
  87 Fixes: c0144beaeca42 ("[XFRM] netlink: Use nla_put()/NLA_PUT() variantes")
  88 Signed-off-by: Eric Dumazet <edumazet@google.com>
  89 Reported-by: syzbot <syzkaller@googlegroups.com>
  90 Cc: Steffen Klassert <steffen.klassert@secunet.com>
  91 Cc: Herbert Xu <herbert@gondor.apana.org.au>
  92 Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
  93 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  94
  95 ---
  96  net/xfrm/xfrm_user.c |    8 +++++---
  97  1 file changed, 5 insertions(+), 3 deletions(-)
  98
  99 --- a/net/xfrm/xfrm_user.c
 100 +++ b/net/xfrm/xfrm_user.c
 101 @@ -1624,9 +1624,11 @@ static inline size_t userpolicy_type_att
 102  #ifdef CONFIG_XFRM_SUB_POLICY
 103  static int copy_to_user_policy_type(u8 type, struct sk_buff *skb)
 104  {
 105 -       struct xfrm_userpolicy_type upt = {
 106 -               .type = type,
 107 -       };
 108 +       struct xfrm_userpolicy_type upt;
 109 +
 110 +       /* Sadly there are two holes in struct xfrm_userpolicy_type */
 111 +       memset(&upt, 0, sizeof(upt));
 112 +       upt.type = type;
 113
 114         return nla_put(skb, XFRMA_POLICY_TYPE, sizeof(upt), &upt);
 115  }