linux-kernel - [PATCH] kasan: fix KASAN_STACK dependency for HW

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Message-Id: <59e75426241dbb5611277758c8d4d6f5f9298dac.1615215441.git.andreyknvl@google.com>
Date:   Mon,  8 Mar 2021 15:58:21 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     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>,
        kasan-dev@...glegroups.com, linux-arm-kernel@...ts.infradead.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>,
        stable@...r.kernel.org
Subject: [PATCH] kasan: fix KASAN_STACK dependency for HW_TAGS

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@...r.kernel.org
Reported-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.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