meminit fix

- Disable gcc-based stack variable auto-init under KASAN (Arnd Bergmann)
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 Comment: Kees Cook <kees@outflux.net>
 
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Merge tag 'meminit-v5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull structleak fix from Kees Cook:
 "Disable gcc-based stack variable auto-init under KASAN (Arnd
  Bergmann).

  This fixes a bunch of build warnings under KASAN and the
  gcc-plugin-based stack auto-initialization features (which are
  arguably redundant, so better to let KASAN control this)"

* tag 'meminit-v5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  structleak: disable STRUCTLEAK_BYREF in combination with KASAN_STACK

security/Kconfig.hardening

@@ -61,6 +61,7 @@ choice
 	config GCC_PLUGIN_STRUCTLEAK_BYREF
 		bool "zero-init structs passed by reference (strong)"
 		depends on GCC_PLUGINS
+		depends on !(KASAN && KASAN_STACK=1)
 		select GCC_PLUGIN_STRUCTLEAK
 		help
 		  Zero-initialize any structures on the stack that may
@@ -70,9 +71,15 @@ choice
 		  exposures, like CVE-2017-1000410:
 		  https://git.kernel.org/linus/06e7e776ca4d3654
 
+		  As a side-effect, this keeps a lot of variables on the
+		  stack that can otherwise be optimized out, so combining
+		  this with CONFIG_KASAN_STACK can lead to a stack overflow
+		  and is disallowed.
+
 	config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
 		bool "zero-init anything passed by reference (very strong)"
 		depends on GCC_PLUGINS
+		depends on !(KASAN && KASAN_STACK=1)
 		select GCC_PLUGIN_STRUCTLEAK
 		help
 		  Zero-initialize any stack variables that may be passed