Messages in this thread | | | Subject | Re: [PATCH] mm: Fix potential pte_unmap_unlock pte error | From | Miaohe Lin <> | Date | Thu, 14 Jan 2021 10:51:24 +0800 |
| |
Hi: On 2021/1/11 1:14, Andi Kleen wrote: > On Sat, Jan 09, 2021 at 03:01:18AM -0500, Miaohe Lin wrote: >> Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged >> high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed, >> we would break the loop with pte unchanged. Then the wrong pte - 1 would >> be passed to pte_unmap_unlock. > > Thanks. > > While the fix is correct, I'm not sure if it actually is a real bug. Is there > any architecture that would do something else than unlocking the underlying > page? If it's just the underlying page then it should be always the same > page, so no bug. >
It's just a theoretical issue via code inspection.
> That said of course the change is the right thing for main line, but probably doesn't > need to be backported. >
So it should not be backported. Should I resend a patch or Andrew would kindly do this?
> -Andi > . >
Many thanks for review and reply.
| |