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    Subject[PATCH v6 06/18] khwasan, arm64: untag virt 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 KHWASAN enabled.

    The solution is to reset the tag in those macros.

    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    ---
    arch/arm64/include/asm/memory.h | 18 ++++++++++++++++++
    1 file changed, 18 insertions(+)

    diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
    index f5e262ee76c1..f5e2953b7009 100644
    --- a/arch/arm64/include/asm/memory.h
    +++ b/arch/arm64/include/asm/memory.h
    @@ -92,6 +92,13 @@
    #define KASAN_THREAD_SHIFT 0
    #endif

    +#ifdef CONFIG_KASAN_HW
    +#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)
    +#endif
    +
    #define MIN_THREAD_SHIFT (14 + KASAN_THREAD_SHIFT)

    /*
    @@ -232,7 +239,12 @@ 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)
    +
    +#ifdef CONFIG_KASAN_HW
    +#define __kimg_to_phys(addr) (KASAN_RESET_TAG(addr) - kimage_voffset)
    +#else
    #define __kimg_to_phys(addr) ((addr) - kimage_voffset)
    +#endif

    #define __virt_to_phys_nodebug(x) ({ \
    phys_addr_t __x = (phys_addr_t)(x); \
    @@ -308,7 +320,13 @@ static inline void *phys_to_virt(phys_addr_t x)
    #endif
    #endif

    +#ifdef CONFIG_KASAN_HW
    +#define _virt_addr_is_linear(kaddr) (KASAN_RESET_TAG((u64)(kaddr)) >= \
    + PAGE_OFFSET)
    +#else
    #define _virt_addr_is_linear(kaddr) (((u64)(kaddr)) >= PAGE_OFFSET)
    +#endif
    +
    #define virt_addr_valid(kaddr) (_virt_addr_is_linear(kaddr) && \
    _virt_addr_valid(kaddr))

    --
    2.19.0.rc0.228.g281dcd1b4d0-goog
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      Last update: 2018-08-29 13:36    [W:4.622 / U:0.008 seconds]
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