[ovs-git] [openvswitch/ovs] 9181a9: pinctrl: Fix DNS packet parsing

Dumitru Ceara noreply at github.com
Wed Aug 28 19:28:44 UTC 2019

  Branch: refs/heads/branch-2.10
  Home:   https://github.com/openvswitch/ovs
  Commit: 9181a9e0bf1bb64ccbbe50080756161654adf745
  Author: Dumitru Ceara <dceara at redhat.com>
  Date:   2019-08-28 (Wed, 28 Aug 2019)

  Changed paths:
    M ovn/controller/pinctrl.c

  Log Message:
  pinctrl: Fix DNS packet parsing

Due to the use of a uint8_t to index inside the DNS payload we could end
up in an infinite loop when specific (invalid) DNS packets were
processed by ovn-controller. In the infinite loop we keep increasing the
query_name dynamic string until running out of memory.

One way to replicate the issue is to configure DNS on the logical switch
and then inject a manually crafted DNS-like packet. For example, with

>>> p = IP(dst='',src='')/UDP(dport=53)/('a'*364)
>>> send(p)

Also add a sanity check on minimum L4 size of packets.

Cherry-picked from ovn commit - 7fbdeaade826da299c20c05050627ebea65fe8c2.

CC: Numan Siddique <nusiddiq at redhat.com>
Fixes: 16cb4fb8ca49 ("ovn-controller: Add 'dns_lookup' action")
Reported-at: https://bugzilla.redhat.com/1740335
Reported-by: Priscila <pveiga at redhat.com>
Signed-off-by: Dumitru Ceara <dceara at redhat.com>
Signed-off-by: Numan Siddique <nusiddiq at redhat.com>
Signed-off-by: Ben Pfaff <blp at ovn.org>

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