Messages in this thread | | | From | Linus Torvalds <> | Date | Wed, 5 May 2021 11:32:17 -0700 | Subject | Re: [PATCH v4 3/4] x86/uaccess: Use pointer masking to limit uaccess speculation |
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On Wed, May 5, 2021 at 1:48 AM David Laight <David.Laight@aculab.com> wrote: > > This would error requests for address 0 earlier - but I don't > believe they are ever valid in Linux. > (Some historic x86 a.out formats did load to address 0.)
Not only loading at address 0 - there are various real reason s why address 0 might actually be needed.
Anybody who still runs a 32-bit kernel and wants to use vm86 mode, for example, requires address 0 because that's simply how the hardware works.
So no. "mask to zero and make zero invalid" is not a proper model.
Linus
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