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    Subject[PATCH 4.7 165/184] cris: buggered copy_from_user/copy_to_user/clear_user
    Date
    4.7-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Al Viro <viro@zeniv.linux.org.uk>

    commit eb47e0293baaa3044022059f1fa9ff474bfe35cb upstream.

    * copy_from_user() on access_ok() failure ought to zero the destination
    * none of those primitives should skip the access_ok() check in case of
    small constant size.

    Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/cris/include/asm/uaccess.h | 75 ++++++++++++++++++----------------------
    1 file changed, 34 insertions(+), 41 deletions(-)

    --- a/arch/cris/include/asm/uaccess.h
    +++ b/arch/cris/include/asm/uaccess.h
    @@ -194,30 +194,6 @@ extern unsigned long __copy_user(void __
    extern unsigned long __copy_user_zeroing(void *to, const void __user *from, unsigned long n);
    extern unsigned long __do_clear_user(void __user *to, unsigned long n);

    -static inline unsigned long
    -__generic_copy_to_user(void __user *to, const void *from, unsigned long n)
    -{
    - if (access_ok(VERIFY_WRITE, to, n))
    - return __copy_user(to, from, n);
    - return n;
    -}
    -
    -static inline unsigned long
    -__generic_copy_from_user(void *to, const void __user *from, unsigned long n)
    -{
    - if (access_ok(VERIFY_READ, from, n))
    - return __copy_user_zeroing(to, from, n);
    - return n;
    -}
    -
    -static inline unsigned long
    -__generic_clear_user(void __user *to, unsigned long n)
    -{
    - if (access_ok(VERIFY_WRITE, to, n))
    - return __do_clear_user(to, n);
    - return n;
    -}
    -
    static inline long
    __strncpy_from_user(char *dst, const char __user *src, long count)
    {
    @@ -282,7 +258,7 @@ __constant_copy_from_user(void *to, cons
    else if (n == 24)
    __asm_copy_from_user_24(to, from, ret);
    else
    - ret = __generic_copy_from_user(to, from, n);
    + ret = __copy_user_zeroing(to, from, n);

    return ret;
    }
    @@ -333,7 +309,7 @@ __constant_copy_to_user(void __user *to,
    else if (n == 24)
    __asm_copy_to_user_24(to, from, ret);
    else
    - ret = __generic_copy_to_user(to, from, n);
    + ret = __copy_user(to, from, n);

    return ret;
    }
    @@ -366,26 +342,43 @@ __constant_clear_user(void __user *to, u
    else if (n == 24)
    __asm_clear_24(to, ret);
    else
    - ret = __generic_clear_user(to, n);
    + ret = __do_clear_user(to, n);

    return ret;
    }


    -#define clear_user(to, n) \
    - (__builtin_constant_p(n) ? \
    - __constant_clear_user(to, n) : \
    - __generic_clear_user(to, n))
    -
    -#define copy_from_user(to, from, n) \
    - (__builtin_constant_p(n) ? \
    - __constant_copy_from_user(to, from, n) : \
    - __generic_copy_from_user(to, from, n))
    -
    -#define copy_to_user(to, from, n) \
    - (__builtin_constant_p(n) ? \
    - __constant_copy_to_user(to, from, n) : \
    - __generic_copy_to_user(to, from, n))
    +static inline size_t clear_user(void __user *to, size_t n)
    +{
    + if (unlikely(!access_ok(VERIFY_WRITE, to, n)))
    + return n;
    + if (__builtin_constant_p(n))
    + return __constant_clear_user(to, n);
    + else
    + return __do_clear_user(to, n);
    +}
    +
    +static inline size_t copy_from_user(void *to, const void __user *from, size_t n)
    +{
    + if (unlikely(!access_ok(VERIFY_READ, from, n))) {
    + memset(to, 0, n);
    + return n;
    + }
    + if (__builtin_constant_p(n))
    + return __constant_copy_from_user(to, from, n);
    + else
    + return __copy_user_zeroing(to, from, n);
    +}
    +
    +static inline size_t copy_to_user(void __user *to, const void *from, size_t n)
    +{
    + if (unlikely(!access_ok(VERIFY_WRITE, to, n)))
    + return n;
    + if (__builtin_constant_p(n))
    + return __constant_copy_to_user(to, from, n);
    + else
    + return __copy_user(to, from, n);
    +}

    /* We let the __ versions of copy_from/to_user inline, because they're often
    * used in fast paths and have only a small space overhead.

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