- Ensure PAN is re-enabled following user fault in uaccess routines
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fix from Will Deacon:
"Ensure PAN is re-enabled following user fault in uaccess routines.
After I thought we were done for 5.4, we had a report this week of a
nasty issue that has been shown to leak data between different user
address spaces thanks to corruption of entries in the TLB. In
hindsight, we should have spotted this in review when the PAN code was
merged back in v4.3, but hindsight is 20/20 and I'm trying not to beat
myself up too much about it despite being fairly miserable.
Anyway, the fix is "obvious" but the actual failure is more more
subtle, and is described in the commit message. I've included a fairly
mechanical follow-up patch here as well, which moves this checking out
into the C wrappers which is what we do for {get,put}_user() already
and allows us to remove these bloody assembly macros entirely. The
patches have passed kernelci [1] [2] [3] and CKI [4] tests over night,
as well as some targetted testing [5] for this particular issue.
The first patch is tagged for stable and should be applied to 4.14,
4.19 and 5.3. I have separate backports for 4.4 and 4.9, which I'll
send out once this has landed in your tree (although the original
patch applies cleanly, it won't build for those two trees).
Thanks to Pavel Tatashin for reporting this and Mark Rutland for
helping to diagnose the issue and review/test the solution"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: uaccess: Remove uaccess_*_not_uao asm macros
arm64: uaccess: Ensure PAN is re-enabled after unhandled uaccess fault
81429eb8d9