datapath: Don't swap table in nlattr_set() after OVS_ATTR_NESTED is found

datapath: Don't swap table in nlattr_set() after OVS_ATTR_NESTED is found

Upstream commit:

    commit 72f17baf2352ded6a1d3f4bb2d15da8c678cd2cb
    Author: Stefano Brivio <sbrivio@redhat.com>
    Date:   Thu May 3 18:13:25 2018 +0200

    openvswitch: Don't swap table in nlattr_set() after OVS_ATTR_NESTED is found

    If an OVS_ATTR_NESTED attribute type is found while walking
    through netlink attributes, we call nlattr_set() recursively
    passing the length table for the following nested attributes, if
    different from the current one.

    However, once we're done with those sub-nested attributes, we
    should continue walking through attributes using the current
    table, instead of using the one related to the sub-nested
    attributes.

    For example, given this sequence:

    1  OVS_KEY_ATTR_PRIORITY
    2  OVS_KEY_ATTR_TUNNEL
    3	OVS_TUNNEL_KEY_ATTR_ID
    4	OVS_TUNNEL_KEY_ATTR_IPV4_SRC
    5	OVS_TUNNEL_KEY_ATTR_IPV4_DST
    6	OVS_TUNNEL_KEY_ATTR_TTL
    7	OVS_TUNNEL_KEY_ATTR_TP_SRC
    8	OVS_TUNNEL_KEY_ATTR_TP_DST
    9  OVS_KEY_ATTR_IN_PORT
    10 OVS_KEY_ATTR_SKB_MARK
    11 OVS_KEY_ATTR_MPLS

    we switch to the 'ovs_tunnel_key_lens' table on attribute #3,
    and we don't switch back to 'ovs_key_lens' while setting
    attributes #9 to #11 in the sequence. As OVS_KEY_ATTR_MPLS
    evaluates to 21, and the array size of 'ovs_tunnel_key_lens' is
    15, we also get this kind of KASan splat while accessing the
    wrong table:

    [ 7654.586496] ==================================================================
    [ 7654.594573] BUG: KASAN: global-out-of-bounds in nlattr_set+0x164/0xde9 [openvswitch]
    [ 7654.603214] Read of size 4 at addr ffffffffc169ecf0 by task handler29/87430
    [ 7654.610983]
    [ 7654.612644] CPU: 21 PID: 87430 Comm: handler29 Kdump: loaded Not tainted 3.10.0-866.el7.test.x86_64 #1
    [ 7654.623030] Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.1.7 06/16/2016
    [ 7654.631379] Call Trace:
    [ 7654.634108]  [<ffffffffb65a7c50>] dump_stack+0x19/0x1b
    [ 7654.639843]  [<ffffffffb53ff373>] print_address_description+0x33/0x290
    [ 7654.647129]  [<ffffffffc169b37b>] ? nlattr_set+0x164/0xde9 [openvswitch]
    [ 7654.654607]  [<ffffffffb53ff812>] kasan_report.part.3+0x242/0x330
    [ 7654.661406]  [<ffffffffb53ff9b4>] __asan_report_load4_noabort+0x34/0x40
    [ 7654.668789]  [<ffffffffc169b37b>] nlattr_set+0x164/0xde9 [openvswitch]
    [ 7654.676076]  [<ffffffffc167ef68>] ovs_nla_get_match+0x10c8/0x1900 [openvswitch]
    [ 7654.684234]  [<ffffffffb61e9cc8>] ? genl_rcv+0x28/0x40
    [ 7654.689968]  [<ffffffffb61e7733>] ? netlink_unicast+0x3f3/0x590
    [ 7654.696574]  [<ffffffffc167dea0>] ? ovs_nla_put_tunnel_info+0xb0/0xb0 [openvswitch]
    [ 7654.705122]  [<ffffffffb4f41b50>] ? unwind_get_return_address+0xb0/0xb0
    [ 7654.712503]  [<ffffffffb65d9355>] ? system_call_fastpath+0x1c/0x21
    [ 7654.719401]  [<ffffffffb4f41d79>] ? update_stack_state+0x229/0x370
    [ 7654.726298]  [<ffffffffb4f41d79>] ? update_stack_state+0x229/0x370
    [ 7654.733195]  [<ffffffffb53fe4b5>] ? kasan_unpoison_shadow+0x35/0x50
    [ 7654.740187]  [<ffffffffb53fe62a>] ? kasan_kmalloc+0xaa/0xe0
    [ 7654.746406]  [<ffffffffb53fec32>] ? kasan_slab_alloc+0x12/0x20
    [ 7654.752914]  [<ffffffffb53fe711>] ? memset+0x31/0x40
    [ 7654.758456]  [<ffffffffc165bf92>] ovs_flow_cmd_new+0x2b2/0xf00 [openvswitch]

    [snip]

    [ 7655.132484] The buggy address belongs to the variable:
    [ 7655.138226]  ovs_tunnel_key_lens+0xf0/0xffffffffffffd400 [openvswitch]
    [ 7655.145507]
    [ 7655.147166] Memory state around the buggy address:
    [ 7655.152514]  ffffffffc169eb80: 00 00 00 00 00 00 00 00 00 00 fa fa fa fa fa fa
    [ 7655.160585]  ffffffffc169ec00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    [ 7655.168644] >ffffffffc169ec80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fa fa
    [ 7655.176701]                                                              ^
    [ 7655.184372]  ffffffffc169ed00: fa fa fa fa 00 00 00 00 fa fa fa fa 00 00 00 05
    [ 7655.192431]  ffffffffc169ed80: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
    [ 7655.200490] ==================================================================

    Reported-by: Hangbin Liu <liuhangbin@gmail.com>
    Fixes: 982b52700482 ("openvswitch: Fix mask generation for nested attributes.")
    Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
    Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>
Tested-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Justin Pettit <jpettit@ovn.org>