[Bug 1972043] Re: Please add -ftrivial-auto-var-init=zero to default build flags

[Dimitri John Ledkov]

@andres can this flag be added to CI builds and start to identify
codepaths that are hindered by this? And start marking them for
uninitialised. Or contribute back to GCC to identify things that are
allocated staright away and skip auto-init of those?

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Title:
  Please add -ftrivial-auto-var-init=zero to default build flags

Status in dpkg package in Ubuntu:
  Confirmed
Status in gcc-12 package in Ubuntu:
  Confirmed
Status in dpkg source package in Kinetic:
  Confirmed
Status in gcc-12 source package in Kinetic:
  Confirmed

Bug description:
  Please add "-ftrivial-auto-var-init=zero" for GCC 12 (which is the
  first release of GCC to provide this flag).

  It goes well with the other important security flaw mitigation flags already enabled in Ubuntu for GCC:
  https://wiki.ubuntu.com/ToolChain/CompilerFlags

  While many variables are initialized (due to -Wuninitialized), there
  is a blind spot for variables passed by reference, padding, and cases
  where -Wuninitialized just fails to track it. Universally wiping the
  variables eliminates nearly the entire class of uninitialized stack
  variable use (https://cwe.mitre.org/data/definitions/457.html) with
  nearly no overhead (e.g. any duplicate assignments will already be
  squashed during dead store elimination, etc).

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