queue-4.4/tipc-check-bearer-name-with-right-length-in-tipc_nl_compat_bearer_enable.patch

   1 From 6f07e5f06c8712acc423485f657799fc8e11e56c Mon Sep 17 00:00:00 2001
   2 From: Xin Long <lucien.xin@gmail.com>
   3 Date: Sun, 31 Mar 2019 22:50:08 +0800
   4 Subject: tipc: check bearer name with right length in tipc_nl_compat_bearer_enable
   5
   6 From: Xin Long <lucien.xin@gmail.com>
   7
   8 commit 6f07e5f06c8712acc423485f657799fc8e11e56c upstream.
   9
  10 Syzbot reported the following crash:
  11
  12 BUG: KMSAN: uninit-value in memchr+0xce/0x110 lib/string.c:961
  13   memchr+0xce/0x110 lib/string.c:961
  14   string_is_valid net/tipc/netlink_compat.c:176 [inline]
  15   tipc_nl_compat_bearer_enable+0x2c4/0x910 net/tipc/netlink_compat.c:401
  16   __tipc_nl_compat_doit net/tipc/netlink_compat.c:321 [inline]
  17   tipc_nl_compat_doit+0x3aa/0xaf0 net/tipc/netlink_compat.c:354
  18   tipc_nl_compat_handle net/tipc/netlink_compat.c:1162 [inline]
  19   tipc_nl_compat_recv+0x1ae7/0x2750 net/tipc/netlink_compat.c:1265
  20   genl_family_rcv_msg net/netlink/genetlink.c:601 [inline]
  21   genl_rcv_msg+0x185f/0x1a60 net/netlink/genetlink.c:626
  22   netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2477
  23   genl_rcv+0x63/0x80 net/netlink/genetlink.c:637
  24   netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  25   netlink_unicast+0xf3e/0x1020 net/netlink/af_netlink.c:1336
  26   netlink_sendmsg+0x127f/0x1300 net/netlink/af_netlink.c:1917
  27   sock_sendmsg_nosec net/socket.c:622 [inline]
  28   sock_sendmsg net/socket.c:632 [inline]
  29
  30 Uninit was created at:
  31   __alloc_skb+0x309/0xa20 net/core/skbuff.c:208
  32   alloc_skb include/linux/skbuff.h:1012 [inline]
  33   netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline]
  34   netlink_sendmsg+0xb82/0x1300 net/netlink/af_netlink.c:1892
  35   sock_sendmsg_nosec net/socket.c:622 [inline]
  36   sock_sendmsg net/socket.c:632 [inline]
  37
  38 It was triggered when the bearer name size < TIPC_MAX_BEARER_NAME,
  39 it would check with a wrong len/TLV_GET_DATA_LEN(msg->req), which
  40 also includes priority and disc_domain length.
  41
  42 This patch is to fix it by checking it with a right length:
  43 'TLV_GET_DATA_LEN(msg->req) - offsetof(struct tipc_bearer_config, name)'.
  44
  45 Reported-by: syzbot+8b707430713eb46e1e45@syzkaller.appspotmail.com
  46 Signed-off-by: Xin Long <lucien.xin@gmail.com>
  47 Signed-off-by: David S. Miller <davem@davemloft.net>
  48 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  49
  50 ---
  51  net/tipc/netlink_compat.c |    7 ++++++-
  52  1 file changed, 6 insertions(+), 1 deletion(-)
  53
  54 --- a/net/tipc/netlink_compat.c
  55 +++ b/net/tipc/netlink_compat.c
  56 @@ -388,7 +388,12 @@ static int tipc_nl_compat_bearer_enable(
  57         if (!bearer)
  58                 return -EMSGSIZE;
  59
  60 -       len = min_t(int, TLV_GET_DATA_LEN(msg->req), TIPC_MAX_BEARER_NAME);
  61 +       len = TLV_GET_DATA_LEN(msg->req);
  62 +       len -= offsetof(struct tipc_bearer_config, name);
  63 +       if (len <= 0)
  64 +               return -EINVAL;
  65 +
  66 +       len = min_t(int, len, TIPC_MAX_BEARER_NAME);
  67         if (!string_is_valid(b->name, len))
  68                 return -EINVAL;
  69