Messages in this thread | | | Date | Wed, 8 Sep 2021 13:34:18 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v2] x86/mm: fix kern_addr_valid to cope with existing but not present entries |
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On Wed, Sep 08, 2021 at 02:22:31PM +0300, Mike Rapoport wrote: > kern_addr_valid() wrongly uses pxy_none() rather than pxy_present() because > according to 9a14aefc1d28 ("x86: cpa, fix lookup_address") there could be > cases when page table entries exist but they are not valid. > So a call to kern_addr_valid() for an address in the direct map would oops. > > I've stopped digging at 9a14aefc1d28 (which is in v2.6.26) and added the > oldest stable we still support (4.4). > > I agree that before 4.19 it's more of a theoretical bug, but you know, > things happen...
Hmmkay, I guess I should add the gist of that to the commit message so that it is explained why 4.4.
I'm assuming the pxy_present() check is more strict than pxy_none() so that backporting to all stable kernels should not introduce any risks...
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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