The xmls are parsed using XML_parser (which is a third party project) and if anything XML_parser needs to be fuzzed.

update engine only calls the XML_parser and just looks at the fields in there. In addition those xmls go through https only and we are sure of their origin. So I don't really know the point of the fuzzers here, But feel free to add yourself to the owners of the update_engine cause cluster fuzz is gonna generate very annoying bugs once in a while and you probably need to take the ownership of fixing the fuzzer bugs :)

Thanks for the feedback! What I thought is operations taken based on the output of XML_parser still can cause crashes or instabilities (besides potential instabilities caused by XML_parser itself). Is that a valid functionality to fuzz on? (I also want to avoid over-testing the code that is deemed unnecessary).

Sure, i'll add myself as an owner.

The following revision refers to this bug:
  https://chromium.googlesource.com/aosp/platform/system/update_engine/+/e3183927f68f1ec2c7bc9c21e48c55c618aabd2a

commit e3183927f68f1ec2c7bc9c21e48c55c618aabd2a
Author: Xiaochu Liu <xiaochu@chromium.org>
Date: Fri Nov 23 03:08:01 2018

update_engine: edit OWNERS

Add xiaochu@google.com to OWNERS so related party can be held
responsible for Chrome OS changes regarding DLC or the fuzzers.

BUG= chromium:906815 
TEST=None

Change-Id: I7769ca704e3d706d14565d9b388e09852d2407db
Reviewed-on: https://chromium-review.googlesource.com/1344913
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>

[modify] https://crrev.com/e3183927f68f1ec2c7bc9c21e48c55c618aabd2a/OWNERS

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/83371ba2b073a53dad9efa5453c4c4849dfdf3ed

commit 83371ba2b073a53dad9efa5453c4c4849dfdf3ed
Author: Xiaochu Liu <xiaochu@chromium.org>
Date: Tue Nov 27 04:31:09 2018

update_engine: install /update_engine_omaha_request_action_fuzzer

Install the fuzzer to proper location.

BUG= chromium:906815 
TEST=USE="asan fuzzer" emerge-kefka update_engine
CQ-DEPEND=CL:1344914

Change-Id: I7e62798ab9c5a0d350fd3aea9ce6dfb7986d12ee
Reviewed-on: https://chromium-review.googlesource.com/1345471
Commit-Ready: Xiaochu Liu <xiaochu@chromium.org>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/83371ba2b073a53dad9efa5453c4c4849dfdf3ed/chromeos-base/update_engine/update_engine-9999.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/f10803fdd973256518a5b3db37cfe8354aca9528

commit f10803fdd973256518a5b3db37cfe8354aca9528
Author: Xiaochu Liu <xiaochu@chromium.org>
Date: Tue Nov 27 04:31:10 2018

chromium-os-fuzzers: add update_engine

Add update_engine as dependency to chromium-os-fuzzers.

BUG= chromium:906815 
TEST=None
CQ-DEPEND=CL:1345471

Change-Id: I1f51c9d3690ed7c96c9b972d4d20db5efe9719d3
Reviewed-on: https://chromium-review.googlesource.com/1351214
Commit-Ready: Xiaochu Liu <xiaochu@chromium.org>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/f10803fdd973256518a5b3db37cfe8354aca9528/virtual/chromium-os-fuzzers/chromium-os-fuzzers-1.ebuild
[rename] https://crrev.com/f10803fdd973256518a5b3db37cfe8354aca9528/virtual/chromium-os-fuzzers/chromium-os-fuzzers-1-r18.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/aosp/platform/system/update_engine/+/399118630bab9615b0237d80cd7c8abbb010a512

commit 399118630bab9615b0237d80cd7c8abbb010a512
Author: Xiaochu Liu <xiaochu@chromium.org>
Date: Tue Nov 27 04:31:09 2018

update_engine: add omaha_request_action_fuzzer target

It fuzzes the XML response sent from Omaha.

It also refactored .gyp file to separate fake*/mock* libraries from
unittest* themselves.

BUG= chromium:906815 
TEST=cros_fuzz

Change-Id: Ic7d0e7d18784e48f4e43b538f9797e5d2d452d08
Reviewed-on: https://chromium-review.googlesource.com/1344914
Commit-Ready: Xiaochu Liu <xiaochu@chromium.org>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>

[add] https://crrev.com/399118630bab9615b0237d80cd7c8abbb010a512/fuzz/xml.dict
[add] https://crrev.com/399118630bab9615b0237d80cd7c8abbb010a512/omaha_request_action_fuzzer.cc
[modify] https://crrev.com/399118630bab9615b0237d80cd7c8abbb010a512/update_engine.gyp