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    SubjectRe: [PATCH v15 09/17] fs, arm64: untag user pointers in copy_mount_options
    On Mon, May 06, 2019 at 06:30:55PM +0200, Andrey Konovalov wrote:
    > This patch is a part of a series that extends arm64 kernel ABI to allow to
    > pass tagged user pointers (with the top byte set to something else other
    > than 0x00) as syscall arguments.
    >
    > In copy_mount_options a user address is being subtracted from TASK_SIZE.
    > If the address is lower than TASK_SIZE, the size is calculated to not
    > allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
    > However if the address is tagged, then the size will be calculated
    > incorrectly.
    >
    > Untag the address before subtracting.
    >
    > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

    Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

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