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Subject[PATCH v8 07/20] kasan, arm64: untag address in __kimg_to_phys and _virt_addr_is_linear
Date
__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@google.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
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