Re: [PATCH v3] x86/uaccess: Use pointer masking to limit uaccess speculation

[Borislav Petkov]

On Thu, Sep 10, 2020 at 12:22:53PM -0500, Josh Poimboeuf wrote:
> +/*
> + * Sanitize a user pointer such that it becomes NULL if it's not a valid user
> + * pointer.  This prevents speculative dereferences of user-controlled pointers
> + * to kernel space when access_ok() speculatively returns true.  This should be
> + * done *after* access_ok(), to avoid affecting error handling behavior.

Err, stupid question: can this macro then be folded into access_ok() so
that you don't have to touch so many places and the check can happen
automatically?

-- 
Regards/Gruss,
    Boris.

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