Messages in this thread | | | From | Dan Williams <> | Date | Mon, 14 Sep 2020 11:48:55 -0700 | Subject | Re: [PATCH v3] x86/uaccess: Use pointer masking to limit uaccess speculation |
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On Mon, Sep 14, 2020 at 10:56 AM Borislav Petkov <bp@alien8.de> wrote: > > 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?
I think that ends up with more changes because it changes the flow of access_ok() from returning a boolean to returning a modified user address that can be used in the speculative path.
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