[Bug 1819936] Re: intermittent panic in 1.6.0-3 due to race in WriteStatus

[Simon Quigley]

I have uploaded the debdiff to Bionic, Cosmic, and Disco.

Thank you for your contribution to Ubuntu, Tiit!

** Also affects: golang-google-grpc (Ubuntu Cosmic)
   Importance: Undecided
       Status: New

** Also affects: golang-google-grpc (Ubuntu Disco)
   Importance: Undecided
       Status: New

** Also affects: golang-google-grpc (Ubuntu Bionic)
   Importance: Undecided
       Status: New

** Changed in: golang-google-grpc (Ubuntu Bionic)
   Importance: Undecided => Medium

** Changed in: golang-google-grpc (Ubuntu Cosmic)
   Importance: Undecided => Medium

** Changed in: golang-google-grpc (Ubuntu Disco)
   Importance: Undecided => Medium

** Changed in: golang-google-grpc (Ubuntu)
       Status: New => Fix Committed

** Changed in: golang-google-grpc (Ubuntu Bionic)
       Status: New => In Progress

** Changed in: golang-google-grpc (Ubuntu Cosmic)
       Status: New => In Progress

** Changed in: golang-google-grpc (Ubuntu Disco)
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/1819936

Title:
  intermittent panic in 1.6.0-3 due to race in WriteStatus

Status in golang-google-grpc package in Ubuntu:
  Fix Committed
Status in golang-google-grpc source package in Bionic:
  In Progress
Status in golang-google-grpc source package in Cosmic:
  In Progress
Status in golang-google-grpc source package in Disco:
  In Progress

Bug description:
  [Impact]

  The version of golang-google-grpc packaged in bionic and cosmic
  (1.6.0-3) crashes intermittently due to a race condition. Upstream bug
  report and pull requests:

  https://github.com/grpc/grpc-go/issues/1111
  https://github.com/grpc/grpc-go/pull/1546
  https://github.com/grpc/grpc-go/pull/1687

  This can cause all packages Built-Using: golang-google-grpc=1.6.0-3 to
  crash as well (see
  https://bugs.launchpad.net/ubuntu/+source/etcd/+bug/1800973).

  The attached debdiff contains two upstream fixes squashed together:

  https://github.com/grpc/grpc-go/commit/22c3f92f5faea8db492fb0f5ae4daf0d2752b19e
  https://github.com/grpc/grpc-go/commit/c6b46087ab923e9f453ec433f99174cdd45b9b89

  These fix the race by synchronizing the entire function.

  [Test Case]

  1. Download the source: apt source golang-google-grpc && cd golang-google-grpc-1.6.0
  2. Patch in the attached test cases: patch -p1 < test-cases-only.patch
     - Theses are part of the upstream patch. Only apply manually to verify problem pre-patch.
  3. Build the package, running the test cases: dpkg-buildpackage --target clean,build
     - Since this is a race condition, the first test case is not guaranteed to fail.
     - The second test case should always fail.

  With the fixes applied there is no need for step 2 (the test cases are
  part of the patch) and step 3 succeeds every time without failure.

  [Regression Potential]

  Regressions are unlikely due to the size and scope of the patch. The
  fix has been applied upstream since 30 Nov 2017 and is still in use in
  the latest release:

  https://github.com/grpc/grpc-
  go/blob/v1.19.0/internal/transport/handler_server.go#L193

  A possible source of regressions would be the squashing of the two
  commits into one. Luckily they were also applied upstream immediately
  one after the other so it should work without problems.

  Another source would be if these patches depended on some other
  changes made since 1.6.0-3. However testing has not revealed this to
  be the case.

  Issues might also arise from my inexperience in updating Ubuntu
  packages and submitting patches for Stable Release Updates.

  [Other Info]

  As golang-google-grpc is a Go library it is linked into other packages
  statically. This means that simply updating this package is not enough
  and dependents need to be rebuilt to benefit from these fixes.

  If this patch is accepted then I plan to open another SRU request to
  set the fixed version as a minimal build dependency for etcd to have
  it also rebuilt and resolve
  https://bugs.launchpad.net/ubuntu/+source/etcd/+bug/1800973.

  Release: Ubuntu 18.04.2 LTS
  Package: golang-google-grpc 1.6.0-3

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