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From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Leon Romanovsky <leonro@mellanox.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Naresh Kamboju <naresh.kamboju@linaro.org>
Subject: [PATCH v3 1/2] arm64: Improve kernel address detection of __is_lm_address()
Date: Fri, 22 Jan 2021 14:37:47 +0000	[thread overview]
Message-ID: <20210122143748.50089-2-vincenzo.frascino@arm.com> (raw)
In-Reply-To: <20210122143748.50089-1-vincenzo.frascino@arm.com>

Currently, the __is_lm_address() check just masks out the top 12 bits
of the address, but if they are 0, it still yields a true result.
This has as a side effect that virt_addr_valid() returns true even for
invalid virtual addresses (e.g. 0x0).

Improve the detection checking that it's actually a kernel address
starting at PAGE_OFFSET.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/include/asm/memory.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 18fce223b67b..99d7e1494aaa 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -247,9 +247,11 @@ static inline const void *__tag_set(const void *addr, u8 tag)
 
 
 /*
- * The linear kernel range starts at the bottom of the virtual address space.
+ * Check whether an arbitrary address is within the linear map, which
+ * lives in the [PAGE_OFFSET, PAGE_END) interval at the bottom of the
+ * kernel's TTBR1 address range.
  */
-#define __is_lm_address(addr)	(((u64)(addr) & ~PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET))
+#define __is_lm_address(addr)	(((u64)(addr) ^ PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET))
 
 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)
-- 
2.30.0


WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com
Cc: Mark Rutland <mark.rutland@arm.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	Leon Romanovsky <leonro@mellanox.com>,
	Alexander Potapenko <glider@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will@kernel.org>, Dmitry Vyukov <dvyukov@google.com>
Subject: [PATCH v3 1/2] arm64: Improve kernel address detection of __is_lm_address()
Date: Fri, 22 Jan 2021 14:37:47 +0000	[thread overview]
Message-ID: <20210122143748.50089-2-vincenzo.frascino@arm.com> (raw)
In-Reply-To: <20210122143748.50089-1-vincenzo.frascino@arm.com>

Currently, the __is_lm_address() check just masks out the top 12 bits
of the address, but if they are 0, it still yields a true result.
This has as a side effect that virt_addr_valid() returns true even for
invalid virtual addresses (e.g. 0x0).

Improve the detection checking that it's actually a kernel address
starting at PAGE_OFFSET.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/include/asm/memory.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 18fce223b67b..99d7e1494aaa 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -247,9 +247,11 @@ static inline const void *__tag_set(const void *addr, u8 tag)
 
 
 /*
- * The linear kernel range starts at the bottom of the virtual address space.
+ * Check whether an arbitrary address is within the linear map, which
+ * lives in the [PAGE_OFFSET, PAGE_END) interval at the bottom of the
+ * kernel's TTBR1 address range.
  */
-#define __is_lm_address(addr)	(((u64)(addr) & ~PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET))
+#define __is_lm_address(addr)	(((u64)(addr) ^ PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET))
 
 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)
-- 
2.30.0


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  reply	other threads:[~2021-01-22 14:40 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 14:37 [PATCH v3 0/2] kasan: Fix metadata detection for KASAN_HW_TAGS Vincenzo Frascino
2021-01-22 14:37 ` Vincenzo Frascino
2021-01-22 14:37 ` Vincenzo Frascino [this message]
2021-01-22 14:37   ` [PATCH v3 1/2] arm64: Improve kernel address detection of __is_lm_address() Vincenzo Frascino
2021-01-22 14:49   ` Catalin Marinas
2021-01-22 14:49     ` Catalin Marinas
2021-01-22 14:37 ` [PATCH v3 2/2] kasan: Add explicit preconditions to kasan_report() Vincenzo Frascino
2021-01-22 14:37   ` Vincenzo Frascino
2021-01-22 14:46   ` Andrey Konovalov
2021-01-22 14:46     ` Andrey Konovalov
2021-01-22 14:58     ` Vincenzo Frascino
2021-01-22 14:58       ` Vincenzo Frascino

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