Messages in this thread |  | | From | James Morse <> | Subject | Re: [PATCH v3 05/17] arm64, hibernate: check pgd table allocation | Date | Fri, 6 Sep 2019 16:17:53 +0100 |
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Hi Pavel,
On 21/08/2019 19:31, Pavel Tatashin wrote: > There is a bug in create_safe_exec_page(), when page table is allocated > it is not checked that table is allocated successfully: > > But it is dereferenced in: pgd_none(READ_ONCE(*pgdp)).
If there is a bug, it shouldn't be fixed part way through a series. This makes it difficult to backport the fix.
Please split this out as an independent patch with a 'Fixes:' tag for the commit that introduced the bug.
> Another issue,
So this patch does two things? That is rarely a good idea. Again, this makes it difficult to backport the fix.
> is that phys_to_ttbr() uses an offset in page table instead > of pgd directly.
If you were going to reuse this, that would be a bug. But because the only page that is being mapped, is mapped to PAGE_SIZE, all the top bits will be 0. The offset calls are boiler-plate. It doesn't look intentional, but its harmless.
Please separate out the potential NULL-dereference bits so there is a clean stand-alone fix that can be sent to the stable trees.
Thanks,
James
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