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    Subject[PATCH 3.16 276/346] ia64: copy_from_user() should zero the destination on access_ok() failure
    3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

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

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

    commit a5e541f796f17228793694d64b507f5f57db4cd7 upstream.

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    [bwh: Backported to 3.16: no calls to check_object_size()]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    --- a/arch/ia64/include/asm/uaccess.h
    +++ b/arch/ia64/include/asm/uaccess.h
    @@ -262,17 +262,15 @@ __copy_from_user (void *to, const void _
    __cu_len; \
    })

    -#define copy_from_user(to, from, n) \
    -({ \
    - void *__cu_to = (to); \
    - const void __user *__cu_from = (from); \
    - long __cu_len = (n); \
    - \
    - __chk_user_ptr(__cu_from); \
    - if (__access_ok(__cu_from, __cu_len, get_fs())) \
    - __cu_len = __copy_user((__force void __user *) __cu_to, __cu_from, __cu_len); \
    - __cu_len; \
    -})
    +static inline unsigned long
    +copy_from_user(void *to, const void __user *from, unsigned long n)
    +{
    + if (likely(__access_ok(from, n, get_fs())))
    + n = __copy_user((__force void __user *) to, from, n);
    + else
    + memset(to, 0, n);
    + return n;
    +}

    #define __copy_in_user(to, from, size) __copy_user((to), (from), (size))

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