linux-kernel - [PATCH 5.11 285/306] kasan: fix KASAN_STACK dependency for HW

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Date:   Mon, 15 Mar 2021 14:55:48 +0100
From:   gregkh@...uxfoundation.org
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrey Konovalov <andreyknvl@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.11 285/306] kasan: fix KASAN_STACK dependency for HW_TAGS

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

From: Andrey Konovalov <andreyknvl@...gle.com>

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.andreyknvl@google.com
Fixes: 6a63a63ff1ac ("kasan: introduce CONFIG_KASAN_HW_TAGS")
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Reported-by: Catalin Marinas <catalin.marinas@....com>
Cc: <stable@...r.kernel.org>
Cc: Will Deacon <will.deacon@....com>
Cc: Vincenzo Frascino <vincenzo.frascino@....com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Marco Elver <elver@...gle.com>
Cc: Peter Collingbourne <pcc@...gle.com>
Cc: Evgenii Stepanov <eugenis@...gle.com>
Cc: Branislav Rankov <Branislav.Rankov@....com>
Cc: Kevin Brodsky <kevin.brodsky@....com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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