[PATCH] kasan: fix KASAN_STACK dependency for HW_TAGS

* [PATCH] kasan: fix KASAN_STACK dependency for HW_TAGS
@ 2021-03-08 14:58 Andrey Konovalov
  0 siblings, 0 replies; only message in thread
From: Andrey Konovalov @ 2021-03-08 14:58 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Catalin Marinas, Will Deacon, Vincenzo Frascino, Dmitry Vyukov,
	Andrey Ryabinin, Alexander Potapenko, Marco Elver,
	Peter Collingbourne, Evgenii Stepanov, Branislav Rankov,
	Kevin Brodsky, kasan-dev, linux-arm-kernel, linux-mm,
	linux-kernel, Andrey Konovalov, stable

There's a runtime failure when running HW_TAGS-enabled kernel built with
GCC on hardware that doesn't support MTE. GCC-built kernels always have
CONFIG_KASAN_STACK enabled, even though stack instrumentation isn't
supported by HW_TAGS. Having that config enabled causes KASAN to issue
MTE-only instructions to unpoison kernel stacks, which causes the failure.

Fix the issue by disallowing CONFIG_KASAN_STACK when HW_TAGS is used.

(The commit that introduced CONFIG_KASAN_HW_TAGS specified proper
 dependency for CONFIG_KASAN_STACK_ENABLE but not for CONFIG_KASAN_STACK.)

Fixes: 6a63a63ff1ac ("kasan: introduce CONFIG_KASAN_HW_TAGS")
Cc: stable@vger.kernel.org
Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 lib/Kconfig.kasan | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 624ae1df7984..fba9909e31b7 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -156,6 +156,7 @@ config KASAN_STACK_ENABLE
 
 config KASAN_STACK
 	int
+	depends on KASAN_GENERIC || KASAN_SW_TAGS
 	default 1 if KASAN_STACK_ENABLE || CC_IS_GCC
 	default 0
 
-- 
2.30.1.766.gb4fecdf3b7-goog


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