| Message ID | 44f4cc7dd6ceb5aac6045e59ff49dce70dd53e74.1525363636.git.sbrivio@redhat.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [ovs-dev,net] openvswitch: Don't swap table in nlattr_set() after OVS_ATTR_NESTED is found | expand |
From: Stefano Brivio <sbrivio@redhat.com> Date: Thu, 3 May 2018 18:13:25 +0200 > 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: ... > 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> Looks good, applied and queued up for -stable. Thanks.
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c index 7322aa1e382e..492ab0c36f7c 100644 --- a/net/openvswitch/flow_netlink.c +++ b/net/openvswitch/flow_netlink.c @@ -1712,13 +1712,10 @@ static void nlattr_set(struct nlattr *attr, u8 val, /* The nlattr stream should already have been validated */ nla_for_each_nested(nla, attr, rem) { - if (tbl[nla_type(nla)].len == OVS_ATTR_NESTED) { - if (tbl[nla_type(nla)].next) - tbl = tbl[nla_type(nla)].next; - nlattr_set(nla, val, tbl); - } else { + if (tbl[nla_type(nla)].len == OVS_ATTR_NESTED) + nlattr_set(nla, val, tbl[nla_type(nla)].next ? : tbl); + else memset(nla_data(nla), val, nla_len(nla)); - } if (nla_type(nla) == OVS_KEY_ATTR_CT_STATE) *(u32 *)nla_data(nla) &= CT_SUPPORTED_MASK;
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> --- net/openvswitch/flow_netlink.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)