linux-kernel - [PATCH v8 07/20] kasan, arm64: untag address in __kimg_to_phys and _virt_addr_is

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Message-Id: <ad3107bea7e337ded9b7192cb637cd4dd983c87b.1537383101.git.andreyknvl@google.com>
Date:   Wed, 19 Sep 2018 20:54:46 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Christoph Lameter <cl@...ux.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Dave Martin <dave.martin@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Ingo Molnar <mingo@...nel.org>,
        Paul Lawrence <paullawrence@...gle.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        kasan-dev@...glegroups.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sparse@...r.kernel.org, linux-mm@...ck.org,
        linux-kbuild@...r.kernel.org
Cc:     Kostya Serebryany <kcc@...gle.com>,
        Evgeniy Stepanov <eugenis@...gle.com>,
        Lee Smith <Lee.Smith@....com>,
        Ramana Radhakrishnan <Ramana.Radhakrishnan@....com>,
        Jacob Bramley <Jacob.Bramley@....com>,
        Ruben Ayrapetyan <Ruben.Ayrapetyan@....com>,
        Jann Horn <jannh@...gle.com>,
        Mark Brand <markbrand@...gle.com>,
        Chintan Pandya <cpandya@...eaurora.org>,
        Vishwath Mohan <vishwath@...gle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v8 07/20] kasan, arm64: untag address in __kimg_to_phys and _virt_addr_is_linear

__kimg_to_phys (which is used by virt_to_phys) and _virt_addr_is_linear
(which is used by virt_addr_valid) assume that the top byte of the address
is 0xff, which isn't always the case with tag-based KASAN.

This patch resets the tag in those macros.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 arch/arm64/include/asm/memory.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 0f1e024a951f..3226a0218b0b 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -92,6 +92,15 @@
 #define KASAN_THREAD_SHIFT	0
 #endif
 
+#ifdef CONFIG_KASAN_SW_TAGS
+#define KASAN_TAG_SHIFTED(tag)		((unsigned long)(tag) << 56)
+#define KASAN_SET_TAG(addr, tag)	(((addr) & ~KASAN_TAG_SHIFTED(0xff)) | \
+						KASAN_TAG_SHIFTED(tag))
+#define KASAN_RESET_TAG(addr)		KASAN_SET_TAG(addr, 0xff)
+#else
+#define KASAN_RESET_TAG(addr)		addr
+#endif
+
 #define MIN_THREAD_SHIFT	(14 + KASAN_THREAD_SHIFT)
 
 /*
@@ -232,7 +241,7 @@ static inline unsigned long kaslr_offset(void)
 #define __is_lm_address(addr)	(!!((addr) & BIT(VA_BITS - 1)))
 
 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
-#define __kimg_to_phys(addr)	((addr) - kimage_voffset)
+#define __kimg_to_phys(addr)	(KASAN_RESET_TAG(addr) - kimage_voffset)
 
 #define __virt_to_phys_nodebug(x) ({					\
 	phys_addr_t __x = (phys_addr_t)(x);				\
@@ -308,7 +317,8 @@ static inline void *phys_to_virt(phys_addr_t x)
 #endif
 #endif
 
-#define _virt_addr_is_linear(kaddr)	(((u64)(kaddr)) >= PAGE_OFFSET)
+#define _virt_addr_is_linear(kaddr)	(KASAN_RESET_TAG((u64)(kaddr)) >= \
+						PAGE_OFFSET)
 #define virt_addr_valid(kaddr)		(_virt_addr_is_linear(kaddr) && \
 					 _virt_addr_valid(kaddr))
 
-- 
2.19.0.397.gdd90340f6a-goog