From: Greg Kroah-Hartman <[email protected]>

From: Andrey Konovalov <[email protected]>

commit d9b571c885a8974fbb7d4ee639dbc643fd000f9e upstream.

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.)

Link: 
https://lkml.kernel.org/r/59e75426241dbb5611277758c8d4d6f5f9298dac.1615215441.git.andreyk...@google.com
Fixes: 6a63a63ff1ac ("kasan: introduce CONFIG_KASAN_HW_TAGS")
Signed-off-by: Andrey Konovalov <[email protected]>
Reported-by: Catalin Marinas <[email protected]>
Cc: <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Peter Collingbourne <[email protected]>
Cc: Evgenii Stepanov <[email protected]>
Cc: Branislav Rankov <[email protected]>
Cc: Kevin Brodsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 lib/Kconfig.kasan |    1 +
 1 file changed, 1 insertion(+)

--- 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
 


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