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Subject[PATCH 5.10 13/57] arm64: Fix kernel address detection of __is_lm_address()
Date
From: Vincenzo Frascino <vincenzo.frascino@arm.com>

commit 519ea6f1c82fcdc9842908155ae379de47818778 upstream.

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).

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

Fixes: 68dd8ef32162 ("arm64: memory: Fix virt_addr_valid() using __is_lm_address()")
Cc: <stable@vger.kernel.org> # 5.4.x
Cc: Will Deacon <will@kernel.org>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210126134056.45747-1-vincenzo.frascino@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/memory.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -238,11 +238,11 @@ static inline const void *__tag_set(cons


/*
- * The linear kernel range starts at the bottom of the virtual address
- * space. Testing the top bit for the start of the region is a
- * sufficient check and avoids having to worry about the tag.
+ * 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) & BIT(vabits_actual - 1)))
+#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)

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