+ kasan-fix-kasan_stack-dependency-for-hw_tags.patch added to -mm tree

+ kasan-fix-kasan_stack-dependency-for-hw_tags.patch added to -mm tree

[akpm]

The patch titled
     Subject: kasan: fix KASAN_STACK dependency for HW_TAGS
has been added to the -mm tree.  Its filename is
     kasan-fix-kasan_stack-dependency-for-hw_tags.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/kasan-fix-kasan_stack-dependency-for-hw_tags.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/kasan-fix-kasan_stack-dependency-for-hw_tags.patch

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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@google.com>
Subject: 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.)

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@google.com>
Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/Kconfig.kasan |    1 +
 1 file changed, 1 insertion(+)

--- a/lib/Kconfig.kasan~kasan-fix-kasan_stack-dependency-for-hw_tags
+++ a/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
 
_

Patches currently in -mm which might be from andreyknvl@google.com are

kasan-mm-fix-crash-with-hw_tags-and-debug_pagealloc.patch
kasan-fix-kasan_stack-dependency-for-hw_tags.patch
kasan-initialize-shadow-to-tag_invalid-for-sw_tags.patch
mm-kasan-dont-poison-boot-memory-with-tag-based-modes.patch